Abstracts of Papers Presented at the 4th Annual Agricultural Research Forum, 19 and 20 March, 1998

Abstracts of Papers Presented at the 4th Annual Agricultural Research Forum, 19 and 20March, 1998Source: Irish Journal of Agricultural and Food Research, Vol. 37, No. 1 (Jun., 1998), pp. 103-139Published by: TEAGASC-Agriculture and Food Development AuthorityStable URL: http://www.jstor.org/stable/25562324 .

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ABSTRACTS OF PAPERS PRESENTED AT THE 4TH ANNUAL AGRICULTURAL RESEARCH FORUM,

19 AND 20 MARCH, 1998

Economic efficiency of suckler beef production O, McEvoy and W. Dunne, Teagasc, Rural Economy Research Centre, 19 Sandymount Avenue, Dublin 4

The objective of this study was to determine the economic impact on spring-born suckler beef produc tion of the switch to direct payments, lower beef prices and feed costs. Feasible growth rates (low and high) for suckler-beef animals were identified from the experi

mental literature. Estimates were based on a cow unit which consists of a suckler cow, 0.5 steer and 0.5 heifer. A one-cut silage system with stocking rates of 1.27 and 1.02 ha/cow unit was assumed for the low and high groups, respectively. Assumed slaughter ages for the steers and heifers, respectively, for the low and high groups, respectively, were 30, 24, 24 and 20 months.

Corresponding carcass weights (CW) were 385, 272,400 and 300 kg. Economic efficiency was measured by mar

gin over feed costs at normal (NI) (IR?2.11/kg CW) and safety net intervention (SNI) (IR?1.58/kg CW) beef prices. At the assumed stocking densities, the maximum direct payments were: the special male beef

premium (SBP), suckler cow premium (SCP) and exten sification on all eligible animals for the low group. The

high group could collect all the SBP, but only 80% of SCP and extensification on both. On a cow unit basis, the feed costs per kilogram CW in the low group were 11% (?0.11) higher than the high group. At NI prices

margins for the low group were: 4% (?26) lower per cow unit, 23% (?141) lower per hectare, but were 2% (?0.04) higher per kg CW. The differentials at SNI

prices were: 3% (?15) lower, 22% (?97) lower and 3% (?0.04) higher. At NI prices, direct payments accounted for 48% and 40% of the margin for the low and high group, respectively. The corresponding figures were 67% and 57% at SNI prices. In conclusion the margins for the high group are more sensitive to beef prices and less stable, but the system is more responsive to mar

kets.

Short duration of dominance of the ovulatory follicle

optimises fertility and synchrony of oestrus E.J. Austin1, M. Mihm1, M.P. Ryan1, D. Williams2 and J.F. Roche1

1Faculty of Veterinary Medicine, University College Dublin, Ballsbridge, Dublin 4 and department of Statistics, Uni

versity College Dublin, Belfield, Dublin 4

In cattle, progestagen treatment of > 12 days gives excellent synchrony of oestrus but marked reductions in pregnancy rate (PR). The aim was to determine if

increasing duration of dominance of the ovulatory folli cle affected synchrony of onset of oestrus and resulted in a gradual or an abrupt decline in PR of heifers. In

experiment 1, duration of dominance was controlled by causing corpus luteum regression at emergence (Dm2, n - 11, mean duration of dominance = 2.1 days) or first

day of dominance of the second follicle wave as de

termined by daily ovarian ultrasound examination, and insertion of a 3 mg Norgestomet implant (N) for dif ferent durations to sustain the dominant follicle as follows: 2 days (Dm4, n = 32), 4 days (Dm6, n =

19), 6

days (Dm8, n = 49), 8 days (Dm 10, n = 28) or 10 days (Dml2, n = 20). In experiment 2, heifers received 15

mg luprositol (Prosolvin?) and N for 3 days (Dm2-4, n = 29) or 7 days (Dm6-8, n = 24) on day 12 of the

cycle. In both experiments heifers detected in oestrus were inseminated approximately 12 h later. In Dm4, the onset of oestrus was delayed relative to all other treatments (P < 0.001) and was less variable than that in Dm6, Dm8 and DmlO heifers (P < 0.1). PR did not

differ between Dm2 (8/9), Dm4 (19/28), Dm6 (14/18) and Dm8 (34/48). DmlO PR (12/23) was lower than Dm2 (P = 0.05) and Dm 12 PR was lower than all other treatments (P < 0.01). In experiment 2, PR was not different between Dm2-4 (22/29) and Dm6-8 (15/24). Thus, onset of oestrus was delayed and less variable in heifers with short dominance. Long durations of domi nance (> 10 days) decreased PR while short and medium durations of dominance gave similarly high PR. It is concluded that short duration of dominance

gives good synchrony and optimum PR in progestagen treated heifers.

Effects of quality of maternal colostrum on serum im munoglobulin levels in suckled calves B. Earley, RJ. Fallon and MJ. Drennan, Teagasc, Grange Research Centre, Dunsany, Co. Meath

The effect of suckler cow breed type on immuno

globulin (Ig) levels of colostrum and subsequent calf serum Ig levels and health status was examined. The herd, which calved indoors, consisted of upgraded Charolais (C: 6 heifers + 10 cows retained from within the herd), Limousin X Friesian (LF: 23 heifers + 41 cows) and Simmental X (Limousin X Friesian) (SLF: 6 cows). Mature cows were bred to Charolais sires while an easy calving Limousin sire was used on heifers.

Following parturition (prior to suckling) a 20 ml colostrum sample was obtained from both the front and hind quarters of the udder. Calves were assisted to suckle, following which they were left with their dam and blood sampled at 48 h and 28 days after birth. Colostrum and calf serum immunoglobulins (mg/ml) were measured quantitatively by single radial im munodiffusion (sRID). In addition, the zinc sulphate turbidity (ZST) test was used on calf serum. There was

no significant breed or udder quarter differences in colostrum IgGt levels. Calves from C cows, C heifers and LF heifers had significantly lower \%GX (35.5 ? 6.5, 36.2 ? 4.99, 38.6 ? 3.13 mg/ml), total Ig serum levels (36.9 ? 4.42,37.6 ? 5.01,40.4 ? 3.19 mg/ml) than calves from LF cows (IgGi

= 53.6 ? 3.03, total Ig = 55.9 ? 3.11

mg/ml) while total Ig levels in calves from C heifers and LF heifers were similar (37.6 ? 5.01 v. 40.3 ? 3.19

103



104 IRISH JOURNAL OF AGRICULTURAL AND FOOD RESEARCH, VOL. 37, NO. 1,1998

mg/ml) at 48 h. The progeny of C cows had lower ZST units than LF cow progeny (P < 0.01). Serum Ig levels in progeny from LF cows were significantly lower at 28

days. SLF cow progeny had similar serum Ig levels and ZST units at 48 h and 28 days. There was no disease in the calves. It is concluded that natural (assisted) suck

ling resulted in high serum Ig levels by 48 h after birth in all calves but values were significantly higher for the

progeny of LF cows.

Current practice in nitrogen usage on grassland W.E. Murphy1, N. Culleton1^. Roche2 and D. Power2

Teagasc, Johnstown Castle Research Centre, Wexford and

Teagasc, Rural Economy Research Centre, 19 Sandy mount Avenue, Dublin 4

Nitrogen usage has risen from 327,700 tonnes in 1984 to 416,900 tonnes in 1996. In the light of increased concern about nitrate levels in ground water, it is in structive to determine how much nitrogen is being applied to grassland. A fertiliser use survey of 1,200 farms that were selected by the Central Statistics Office on the basis of farm size and farming system was carried out in 1995. Mean N usage for total grassland was 103 kg/ha. Mean N usage on hay crops was 56

kg/ha which is significantly lower than the Teagasc N recommendation of 80 kg/ha. Mean N usage on silage

was 117 kg/ha, which is broadly in line with Teagasc recommendations. Mean N usage on grazing land was 93 kg/ha. Dairying used the highest rate of N (166 kg/ha) while cattle rearing used the lowest rate (39 kg/ha). Nitrogen usage was directly related to stocking intensity. At stocking rates of 1.0 to 1.5 livestock units

(LU)/ha mean N usage was 82 kg/ha. At these stock

ing rates Teagasc recommendations are zero N usage and use of Trifolium repens to fix atmospheric N is advocated. At stocking rates of 2.0 to 2.5 LU/ha, mean N usage was 179 kg/ha, which is higher than is recom mended. Calcium ammonium nitrate, 18-6-12 and high N compounds account for 19.2, 34.6 and 34.3% of all

nitrogen containing fertiliser used on grassland.

Gross nitrogen transformation rates in grass swards G.L. Travers1'2, CJ. Watson1, AS. Laidlaw1 and E.G. O'Riordan2

Faculty of Agriculture and Food Science, The Queen's University of Belfast, Newforge Lane, Belfast BT9 5PX and Teagasc, Grange Research Centre, Dunsany, Co.

Meath

The fundamental processes of gross N mineralisation and immobilisation can only be properly studied using isotope techniques. The aim of the current study was to examine endogenous gross transformations of N in ro

tationally grazed grass and grass/clover swards on both

permanent and reseeded pasture. The experiment was laid out in a 2x2 factorial design with treatments

replicated four times. Paired soil incubations were un dertaken at 13.5?C using differentially 15N labelled

15NH4N03 applied in solution at a rate of 2 figN g~l oven dry soil and at an enrichment of 99.7 atom % excess. The change in concentration and enrichment of the NH4-N and NO3-N pools were determined at time intervals of 0, 1, 3, 7, 14 and 21 days. Gross mineralisa

tion rates were calculated from the decline in the

15NH? pool, gross nitrification rates were calculated from the decline in the 15N03 pool and gross immobil isation rates were calculated by difference. The 15N enrichment of the NH4 pool fell dramatically within the first 24 h of the study and remained at just above natural abundance thereafter. Daily mineralisation and immobilisation rates were higher (P < 0.01 and P < 0.05, respectively) on the grass/clover swards compared to the grass sward. However, there was no significant difference between the permanent and reseeded pas tures. The grass/clover sward on the permanent pas ture had a significantly higher (P < 0.05) gross nitrifi cation rate than all other treatments. It is concluded that the 15N pool dilution technique used in this study showed that grass/clover swards have a higher N turnover rate compared to grass swards.

Current practice in phosphorus usage on grassland N. Culleton1, W.E.

Murphy1, B. Coulter1, M. Roche2,

D. Power2 and H. Tunney1 1 Teagasc, Johnstown Castle Research Centre, Wexford and

2Teagasc, Rural Economy Research Centre, 19 Sandy mount Avenue, Dublin 4

A survey of 45,000 soil samples received for nutrient

analysis at Johnstown Castle Research Centre in 1996 was undertaken to determine the P status of Irish soils. A fertiliser use survey of 1,200 farms was conducted

nationally in 1995, to determine how much fertiliser P was used pn grassland. The survey of soil samples revealed that 21%, 35%, 23% and 21% of soils had P levels (Morgan's extract) of < 3, 3.1-6, 6.1-10 and > 10 mg/kg soil, respectively. The national survey showed that mean P usage on grazing land was 11

kg/ha. At stocking rates of 1.0 to 1.5 livestock unit (LU)/ha, the mean P usage was 12 kg/ha, while at

stocking rates of 2.0 to 2.5 LU/ha, mean P usage was 17 kg/ha. P usage at all stocking rates, and especially at low stocking rates, exceeded Teagasc recommenda tions. The survey also revealed that mean P usage on

silage land was 20 kg/ha. It is concluded that too much

phosphatic fertiliser is used on silage land and there is considerable scope for reductions in P usage without

reducing productivity.

The effect of cutting on soil potassium under grass P.A. Blagden and W.E. Murphy, Teagasc, Johnstown Castle Research Centre, Wexford

The growth and removal of a cut of silage removes a

quantity of K from the soil, and causes a reduction in the level of available soil K. Data from a long-term grazing/cutting experiment were examined to de termine the effect of initial soil K level on the yield of the following silage cut, and on K level after cutting.

Maximum silage dry matter (DM) yield (4.8 t/ha) was obtained where soil K was greater than 90 mg/1 (Morgan's extract), where K uptake was not less than 100 kg/ha, and herbage K concentration was over 20

g/kg in the DM. Higher initial soil K levels resulted in increased K uptake and higher grass K concentrations,

but not in greater yield. Consequently higher soil K levels suffered greater reductions following cutting, ac



ABSTRACTS: AGRICULTURAL RESEARCH FORUM 105

cording to the equation: Decrease in soil K= 0.4082 X initial soil K (R2 0.97). At low initial soil K levels (about 40 mg/1) the reduction after cutting was small in comparison to yield and the amount of K removed.

This indicates that some of the K removed came from non-extractable soil K From these preliminary results, it is concluded that estimates of the effect of cutting on soil K should refer to initial soil K status in addition to

yield.

Assessing the accuracy of current fertiliser recommen dations for grassland using plant tissue analysis R.M. Dils, J.S. Bailey and R.H. Foy, Department of Agricultural and Environmental Science, The Queen's University of Belfast, Newforge Lane, Belfast, BT9 5PX

Successful nutrient management is critically dependent on satisfying the nutrient requirements of field crops. The objective of this research was to evaluate the accuracy of current phosphorus (P) and potassium (K) fertiliser recommendations for silage grass in Northern Ireland using diagnostic plant tissue analysis. Grass

samples were taken from selected silage fields on five farms in Co. Fermanagh, and chemically analysed. In addition, herbage analysis results from several field

experiments carried out in Northern Ireland were available to supplement the data base. These results

were then interpreted using the Diagnosis and Recom mendation Integrated System (DRIS) which identifies nutrient imbalances using multiple ratios of the ele ments N, P, K, S, Mg and Ca. In theory, if a nutrient recommendation is correct, a plot of the appropriate

DRIS index (y-axis) versus the nutrient application rate minus the nutrient recommendation rate (x-axis), should pass through the optimum + 5 index at zero on the x-axis. If, however, the line crosses the + 5 index at a negative value on the x-axis, then the amount of nutrient recommended is greater than that needed for

optimum production. Accordingly, P recommendations for first-cut silage proved to be too high on coarse textured soils (4 to 13 kg P/ha) but correct on fine textured soils. For second-cut silage, P recommenda tions appeared to be correct on all soil types. Current

K recommendations for first and second cuts were found to be too high on all soils by 25 and 17 kg K/ha, respectively. In conclusion, the results of this research

suggest that P recommendations for first-cut silage, and K recommendations for first- and second-cut silage, could be lowered significantly without causing loss in

crop productivity.

Phosphorus fertiliser use in relation to intensity of

grassland use H. Tunney1, D. Power2, W. Murphy1, J. Heavey2, N. Culleton1 and M. Roche2

Teagasc, Johnstown Castle Research Centre, Wexford and 2 Teagasc, Rural Economy Research Centre, 19 Sandy

mount Avenue, Dublin 4

The use of P on grassland farms was examined, at different stocking rate intensities throughout the coun

try, based on the data extracted from the 1996 National Farm Survey (NFS) and Central Statistics Office (CSO) information. In the NFS, data were collected from 1168

farms of which 1148 had grassland. The methods used were similar to those published in the 1995 NFS. For this paper, data were extracted for farms with more than two livestock units. These farms were representa tive of 126,000 farms. The total grassland, rough graz ing and forage area for all farms represented by the

study were 3.25, 0.51 and 3.85 million ha, respectively, based on CSO data and the total number of livestock units (LU) was 5.82 million. The area represented by the survey was subdivided into seven different stocking rate (SR) categories and the distribution of average P use (per ha and per LU) was estimated. The stocking rates were expressed on total grassland area including rough grazing. Approximately 32.5% (1.056 m ha) of

grassland had over 2.0 LU/ha compared with 38.5% under 1.5 LU/ha, the remaining 29% had between 1.5 and 2.0 LU/ha. For the following SR categories < 1, 1.0-1.25, 1.25-1.5, 1.5-1.75, 1.75-2.0, 2.0-2.25 and > 2.25 LU per ha the average P used on the grassland only area was 8.9,10.2, 13.7, 15.9,18.8,16.6 and 20.9 kg per ha, respectively. Expressed on total forage area it varied from 5.3 to 19.6 kg P per ha. More than 50% of the rough grazing in the country was on farms with less than one LU per ha of forage. The P applied (kg/ha)

on a grassland basis was more than twice as high for the highest compared to the lowest SR categories. Esti

mates of average fertiliser P used per LU were 9.0, 8.6, 9.5, 9.4, 9.7, 7.6 and 8.0 kg P for farms in the SR

categories < 1, 1.0-1.25, 1.25-1.5, 1.5-1.75, 1.75-2.0, 2.0-2.25 and > 2.25 LU per ha, respectively. These estimates are remarkably constant across the stocking rate categories (9 kg approximately) and are more than double the P removal in milk and meat and supports other studies indicating that there is a potential for considerable savings on fertiliser P inputs on many grassland farms in Ireland.

The impact of direct payments on calf prices W. Dunne1, J.J. O'Connell2 and U. Shanahan1

Teagasc, Rural Economy Research Centre, 19 Sandy mount Avenue, Dublin 4 and Department of Agribusi ness, University College Dublin, Belfield, Dublin 4

The objective was to study the effect of the switch to direct payments (DP), under the Common Agricultural Policy of the EU, on the prices of calves and young cattle. Three approaches were used: (a) the price of a male Friesian calf was compared with the value of a 320 kg steer carcass classified as R3, (b) the margins for different types of cattle enterprises in the National Farm Survey (NFS) were evaluated to determine their relative dependency on DP, (c) the price differentials for male calves in Ireland and other EU countries were

compared to determine if they were related to the

capacity to collect DP. It was estimated that ?35 to ?40 was being bid into the calf price due to DP. The market-based component of margins declined for all

types of cattle enterprises since 1992, but the percent age decline was least for rearing (29%) and most for

fattening systems (61%). This indicates that DP is be

ing capitalised into the price of calves and young ani mals. Results showed that the price of male Friesian calves in Ireland increased relative to those in other member states. The greatest increase was relative to calves destined for veal and bull-beef production, which, respectively, collect no or a restricted amount of DP. It




was concluded that the capitalisation process increases as the male animal moves along the production chain and indirectly increases the demand for, and prices of, heifer calves. When the ownership of animals changes the capitalised value is released to the seller but be comes a cost for the next-stage purchaser. Since ani

mals are highly tradable, the flow of DP to various

groups of producers also creates a counter-flow of DP induced costs that progressively increase along the

beef-production chain.

Growth, digestibility and rumen fermentation in beef cattle offered rations which differed in starch form and concentration

A.P. Moloney and MJ. Drennan, Teagasc, Grange Re search Centre, Dunsany, Co. Meath

The hypothesis tested in this study was that the opti mum level of starch inclusion in a high concentrate ration for beef cattle is influenced by its degree of

processing. Sixty Friesian bulls (initial body weight (BW) 401 kg), were assigned to five treatments. They were

penned in pairs and offered ad libitum a ground and

pelleted ration containing either 139, 239 or 327 g starch/kg dry matter (DM), a coarse ration based on rolled barley, corn gluten and sugar-beet pulp (BP, 311

g starch/kg DM) or a coarse ration based on rolled

barley and soyabean meal (BS, 492 g starch/kg DM). The rations were formulated to be isonitrogenous and

isoenergetic and were offered for 19 weeks prior to

slaughter. Digestibility in vivo and rumen fermentation were measured in Friesian steers (n =

6/treatment) in a parallel study. Increasing starch concentration in a

ground and pelleted ration decreased (P < 0.05) daily DM intake, carcass growth and the acetate to propio nate ratio (A:P) in rumen fluid (154, 15.9 and 13.9 (s.e.d. 0.50) kg/pair, 594, 646 and 568 (s.e.d. 46.5) g/day and 2.25, 1.72 and 1.16 (s.e.d 0.339) in cattle offered rations containing 139, 239 and 327 g/kg starch, respectively) but did not affect in vivo digestibility. At similar starch concentration, grinding decreased (P <

0.05) daily DM intake (13.9 v. 17.3 kg/pair), carcass

growth (568 v. 685 g/day) and the A:P in rumen fluid (1.16 v. 2.85) without affecting in vivo digestibility.

Organic matter digestibility of BS was higher (P < 0.05) than that of BP (805 v. 749 g/kg) but metabolisable

energy intake and carcass growth were similar. Steers offered BS had a lower (P < 0.05) A:P in rumen fluid (1.20 v. 2.85). It is concluded that (1) grinding decreases the optimum starch inclusion level in concentrates of fered ad libitum to beef cattle, and (2) increasing starch concentration and grinding rather than rolling in creases propionate production in the rumen.

The effect of level of feeding and foragexoncentrate ratio on the dry matter degradability of concentrate

ingredients in steers V.B. Woods1, A.P. Moloney1 and F.P. O'Mara2

Teagasc, Grange Research Centre, Dunsany, Co. Meath and Faculty of Agriculture, University College Dublin, Belfield, Dublin 4

There is a need to standardise the in sacco procedure

for ruminal evaluation of feed ingredients. The objec tive of this experiment was to examine the effect of level of feeding and foragerconcentrate ratio on the dry

matter (DM) degradability of concentrate ingredients in the rumens of steers. Six ruminally fistulated steers

were offered three ratios of grass silage to pelleted concentrate (250:750, 500:500 and 750:250 g/kg DM) at 11 g and 17 g DM/kg body weight, in a 6 (treat

ments) x 6 (21-day periods), latin square experiment. The pelleted concentrate composition was copra meal 139 g/kg, corn gluten 143 g/kg, soya hulls 136 g/kg, barley 146 g/kg, fishmeal 15 g/kg, and soyabean meal 15 g/kg together with citrus pulp 141 g/kg, beet pulp 141 g/kg, distillers grains 104 g/kg and

minerals/vitamins 20 g/kg. Nylon bags containing 1.5 g ground (2 mm screen) test feed (first six listed) were incubated in duplicate in animals for 0, 2, 4, 8, 14, 24 and 48 h. Residual DM was measured by oven drying at 40?C for 48 h after agitation using a stomacher labora

tory blender 400 and washing. Disappearance of con centrates at each incubation time was expressed rela tive to the weight of the original feed which was non

incubated, non-stomached and non-washed. Statisti

cally, DM disappearance of each of the six test feeds was examined individually. Neither grass silage-.con centrate ratio in the diet nor level of feeding had a

significant effect on the DM disappearance at any in cubation time for any of the ingredients examined. There were no significant diet by level, diet by time, level by time or diet by level by time interactions. The

mean (s.d.) DM proportions which disappeared over 48 h incubation for copra meal, corn gluten, soya hulls, barley, fishmeal and soyabean meal were 0.60 (0.002), 0.64 (0.009), 0.44 (0.019), 0.78 (0.004), 0.43 (0.025) and 0.72 (0.009), respectively. It is concluded that feeding level and the rate of inclusion of grass silage in a

silage-concentrate diet did not affect the DM degrad ability of concentrate ingredients.

Effect of forage maturity and ensiling on the fermenta tion kinetics of the cell wall component of perennial ryegrass

M.C. Hickey1, AP. Moloney1 and M. O'Connell2 1 Teagasc, Grange Research Centre, Dunsany, Co. Meath

and Dublin City University, Glasnevin, Dublin 9

The effects of increasing maturity (M) and ensiling (E) on the rumen fermentation kinetics of perennial rye grass neutral detergent fibre (NDF) were examined. The Tilley and Terry dry matter digestibility (DMD) technique was evaluated for its ability to detect chang ing rumen NDF fermentation patterns. Grass plots

were closed on the 17 March and subsequently har vested at 7, 10, 12 and 16 weeks of growth. Grass (G) was ensiled under restrictive (5 ml formic acid/kg, F) and extensive (20 g sucrose/kg, S) conditions. The NDF and acid detergent fibre (ADF) concentrations of

forages at 7, 10, 12 and 16 weeks of growth were 493, 547, 579, 635 (s.e. 6.12) and 258, 288, 336, 371 (s.e. 3.79)

g/kg DM, respectively. There was a significant MxE interaction for hemicellulose (HC = NDF-ADF) con centration. The HC concentrations of G, S and F were

235, 205, 192; 259, 210, 196; 243, 217, 238 and 264, 223, 234 (s.e. 3.94) for weeks 7, 10, 12 and 16, respectively. On each day of harvesting or silo opening, fresh forages




were incubated in vitro and sampled (n = 3) 11 times over 96 h. NDF residues were calculated for each time

point. There was a significant interaction between all

experimental factors with respect to NDF digestion. Ensiling decreased the initial rate of fibre digestion with 241, 117 and 58 (s.e 19.07) g NDF digested/kg NDF at 24 h for G, F and S, respectively. For forages grown for 12 and 16 weeks, ensiling significantly ex tended the NDF lag time to > 24 h. When compared

with G, the extent of NDF digestion for S was de creased for weeks 7 and 12 (890 v. 717 and 732 v. 584

g/kg (s.e. 1.907)), and increased for week 14 (377 v. 486). Silage F had a lower extent of digestion in week 10 (732 v. 584 g /kg). Ensiling significantly increased (P < 0.05) the DMD of G (702, 723 and 719 (s.e. 4.16)

g/kg for G, F and S, respectively). It is concluded that

ensiling has a negative impact on subsequent rumen NDF fermentation patterns, which is not reflected in DMD values.

Big bale and precision-chop silage systems: conserva tion characteristics and silage nutritive value for beef cattle P. O'Kiely1, JJ. Lenehan1 and D. Forristal2 Teagasc, Grange Research Centre, Dunsany, Co. Meath

and Teagasc, Oak Park Research Centre, Carlow

The aim was to identify the critical factors distinguish ing the conservation efficiency and nutritive value of

silage produced using precision-chop or big bale silage systems. Alternating rows of grass mown on 17 July

were allocated to the following conservation treat ments: precision-chop, unwilted (PU); precision-chop, unwilted plus formic acid (2.4 1/t) (PUF); precision chop, wilted (PW); big bale, wilted (BW) and big bale,

wilted and pre-chopped (BWC). Wilting was for ap proximately 30 h. Big bales were made (Claas Rollant 46 Roto Cut) with the slicing blades engaged on alter nate rows of grass. Fifteen Charolais-crossbred heifers allocated to each treatment were offered silage ad libitum for 118 days, supplemented with 2 kg concen trates per head daily. In parallel, in vivo digestibility of diets was determined on three occasions using 10 Friesian steers. BW and BWC silages had similar in

storage losses and aerobic stability, while PW silages were aerobically less stable at feedout. The mean (s.d.) respective dry matter (DM) concentrations for PU, PUF, PW, BW and BWC silages were 205 (15.8), 219 (16.7), 387 (9.4), 355 (33.7) and 362 (38.1) g/kg. Corre

spondingly, carcass gains were 557, 580, 561, 517 and 517 (s.e. 25.5) g/day (P > 0.05); silage DM intakes were

6.1, 6.5, 7.2, 7.4 and 7.0 (s.e. 0.07) kg/day (P < 0.001); in vivo DM digestibility proportions were 739, 727, 721, 743 and 741 (s.e. 7.3) g/kg (P > 0.05); silage DM in

take/live-weight gain values were 7.1, 7.2, 9.4, 9.5 and 9.5 (s.e. 0.52) kg/kg (P < 0.001); and silage DM in

take/carcass gain values were 11.5, 11.4, 13.2, 14.8 and 13.9 (s.e. 0.60) kg/kg (P < 0.001). It is concluded that

both harvesters produced wilted silages of similar nutri tive value for finishing beef cattle, that chopping forage at baling did not alter its conservation efficiency or nutritive value, that under good ensiling conditions formic acid did not alter silage nutritive value and that

wilting increased the feed required per kg live-weight and carcass weight gains.

The genetic correlation between performances at dif ferent grades for showjumping horses in Ireland L.I. Aldridge, D.L. Kelieher, M. Reilly and P.O. Bro

phy, Faculty of Agriculture, University College Dublin, Belfield, Dublin 4

In Ireland, as in many other countries, showjumping horses start their careers in the novice grades and as their accumulated points reach certain specific thresh old values, they are reclassified, into successively higher grades. The purpose of this project was to determine the value of performance at novice or 'Low* grade for

predicting genetic merit at 'High' grades. Calculating the heritability of performance at novice grades and the genetic correlation between high and novice grades

was used to evaluate this predictive value. The measure of performance used in genetic evaluation of

showjumping horses in Ireland is obtained from the

ranking of all performances in all competitions based on the number of faults and the times in a round for each horse. The amount of data available for analysis consisted of 160,412 performance records for 6,786 horses in 7,313 competitions covering the years 1993

through to 1996. For the purpose of analysis, competi tions were assigned to one of three levels, namely high,

medium or low, with each level regarded as a different trait. The genetic correlation between the traits and their heritabilities were estimated by restricted maxi

mum likelihood procedures. The genetic correlation between performances at high and low levels was 0.65 (s.e. 0.16), between medium and low 0.96 (s.e. 0.04) and between medium and high 0.73 (s.e. 0.10). The heri

tability of performance at high level was 0.08, at medium level 0.05 and at low level 0.03. These esti mates indicate that low (novice) grade performances can be useful in predicting an animal's potential ge netic merit for high grade performance. From these estimates a multitrait BLUP analysis could be carried out to predict the genetic merit of animals for perfor mance in high grade competitions.

Impact of estimating flock effects on the precision of

genetic evaluation of rams E. Wall, D.L. Kelieher and V. Olori, Faculty of Agricul ture, University College Dublin, Belfield, Dublin 4

The accuracy of an estimated breeding value (EBV) depends on the amount of information available from the animal, its relatives and the effect of non-genetic factors. Under the Sire Reference Scheme (SRS) for

Charollais and Texel sheep, animals are compared across flocks. Separating non-genetic flock effects from animal genetic effects can be done only if the flocks are

genetically connected which occurs when the same rams are used in several flocks. The aim of this study was to examine the genetic connectedness between the flocks in the SRS and to determine its effect on the precision

of estimated breeding value of rams. EBVs and their

precision for live weight at 120 days of age were esti mated for 80 Texel and 57 Charollais sires using animal model Best Linear Unbiased Prediction. The number of flocks in which a given sire was used and the number of progeny of the sire in each flock were used as indicators of connectedness between rams and flocks,




respectively. The strength of the connectedness de

pends on the number of the offspring of common sires in the different flocks. Precision was highly dependent

on the number of offspring per ram. The loss in preci sion with or without the flock effects in the model

depended on the distribution of the offspring of a ram

among flocks. Rams with many offspring in one flock had high precision but also had the highest drop in

precision with the inclusion of flock effects. Results show that poor connections between flocks affect the EBV by reducing the accuracy of the prediction. Guidelines for the SRS should be centred on the more extensive use of the reference sires to create the con nections between the flocks and provide for sufficient

progeny per sire so that precision of evaluation will not be seriously reduced.

The effect of age at measurement on the prediction of live weight, muscle depth and fat depth in Iambs

EJ. Crosby, D.L. Ketteher, V.E. Olori and M. Reilly, Faculty of Apiculture, University College Dublin, Belfield, Dublin 4

The new Sire Referencing Scheme in sheep aims to

improve carcass quality in lambs through genetic means. Texel (Tex) and Charollais (Char) terminal sire breeds are involved in this scheme. An animal's performance is measured at one visit to each farm when the mean flock age is approximately 120 days. Measurements taken are live weight (LW), ultrasonic muscle depth (UMD) and ultrasonic fat depth (UFD). Due to varia tion in date of birth, actual ages at recording range from about 80 to 160 days. This means that the mea surements used to estimate breeding values are pre dicted measurements, calculated using predetermined linear adjustment factors. A different factor used for each trait in both breeds. The aim of this study was to determine how good these adjustments are in predict ing the 120-day LW, UMD and UFD, and to see if animals recorded at a younger age are biased. To determine this, an additional set of measurements was taken when the mean flock age was approximately 90

days (first record). These 90-day records were then used to estimate the 120-day records (second record) to see if there was a disparity between the two. Results showed that correlations between predicted and actual measurements were high for LW [0.89 (Tex), 0.88 (Char)l, lower for UMD [0.55 (Tex), 0.64 (Char)l and lowest for UFD [0.45 (Tex), 0.43 (Char)]. On average,

LW was under predicted [-1.46 kg (Tex), -0.94 kg (Char)], UFD was over predicted [0.29 mm (Tex), 0.36

mm (Char)] and UMD differed between breeds [? 1.47 mm (Tex), 1.43 mm (Char)]. Individual animals varied

considerably (e.g. disparity in Texel LW ranged from -10.30 kg to 11.55 kg). Analysis of variance showed that the disparity was mainly accounted for in individ ual animal to animal growth rates.

A comparison of lamb output from Texel, Rouge de POuest and Texel X Rouge ewes L.O.W. McClinton and A.F. Carson, Agricultural Re search Institute of Northern Ireland, Hillsborough, Co.

Down BT26 6DR

Previous studies have shown that increasing the pro

portion of Rouge de 1'Ouest (Rouge) genes and, more

particularly, Texel genes in ewes leads to improvements in lamb carcass quality. However, problems of dystocia

have been identified in pure-bred Texel ewes and lamb

mortality with pure-bred Rouge ewes. The objectives of this experiment were to investigate the effect of using ewes which were hybrids of two continental breeds in

comparison to those of a single continental breed. Ef fects of plane of nutrition in late pregnancy on dystocia and lamb output were also examined. Rouge (n =

71), Texel (n = 63) and hybrid (Texel X Rouge) ewes (n =

33) were split into groups balanced for age, condition score, previous litter size and allocated to Rouge or

Texel sires. Ewes remained at grass until 8 weeks prior to lambing, when ewes were shorn and housed individ

ually or in pairs and allocated to nutritional regimes estimated to provide 70, 100 and 140% of metabolis able energy and protein requirements, respectively. The

foragexoncentrate ratio was the same for all treat ments. Prolificacy was significantly lower in Texel com

pared to Rouge (P < 0.001) ewes while hybrid ewes were intermediate. Ewe breed had no significant effect on lamb birth weight. In contrast to previous studies, dystocia was not significantly higher with Texel ewes.

Hybrid ewes produced significantly more lambs born alive than Texel ewes (P < 0.05). Yield of milk fat plus

milk protein did not vary significantly among the ewe breeds. Overall lamb output per ewe did not vary sig nificantly between the breed types. The planes of nutri tion imposed in late pregnancy had no significant effect on dystocia or lamb viability.

Ewe fertility following cervical Al of fresh or frozen thawed semen at a natural or synchronised oestrus

A. Donovan1, J.P. Hanrahan1, E. Kummen2, P. Duffy3 and M.P. Boland3 1 Teagasc, Research Centre, Athenry, Co. Galway, Norsk

Rodt Fe, Trondheim, Norway and Faculty of Agriculture, University College Dublin, Belfield, Dublin 4

Conception rates of approximately 60% have been re

ported for Norwegian sheep following cervical insemi nation with frozen-thawed semen. The objectives were to compare frozen semen from Norwegian (NOR) and Irish (IRL) rams and examine the effects of ewe breed, synchronisation and operator on pregnancy rate. Parous ewes (n

= 297), of mixed breeds were inseminated to a

natural (N) or synchronised (S) oestrus with either fresh or frozen-thawed semen (IRL and NOR). Ewes

were randomly assigned, within breed, to: (i) N fresh: n = 28, (ii) S fresh: n = 30, (iii) N-IRL: n = 62, (iv) S-IRL: n = 50, (v) N-NOR: n - 68, (vi) S-NOR: n - 59.

Within each group, half were inseminated by a Norwe

gian and half by an Irish operator. Pregnancy rate did not differ significantly between ewes inseminated to a natural or synchronised oestrus nor between Norwe

gian and Irish frozen semen. The proportion of ewes

pregnant after insemination with fresh semen was 0.82 and 0.70 (treatments (i) and (ii)) compared with 0.40, 0.52, 0.34 and 0.37 (treatments (iii) to (vi)) for frozen semen (P < 0.001). Corresponding litter sizes (? s.e), adjusted for ovulation rate, were 2.9 ? 0.22, 3.3 ? 0.23, 2,2 ? 0.21, 1.7 ? 0.21, 2.2 ? 0-21 and 2.1 ? 0.21 (fresh v.

frozen; P < 0.001). There was an interaction between semen type (fresh or frozen) and oestrus type for litter size due to an increased adverse effect of frozen semen




on litter size in synchronised ewes (P < 0.05). Breed of ewe and operator significantly influenced pregnancy rate (P < 0.01) and these effects did not depend on semen type. These results suggest a potential role for cervical insemination using frozen-thawed semen in

sire-referencing schemes.

Deriving phosphorus export coefficients for CORINE land cover types S.O. McGuckin, C. Jordan and R.V. Smith, Department of Agricultural and Environmental Science, The Queen's University of Belfast, Newforge Lane, Belfast BT9 5PX

Agriculture is now recognised as a major source of

phosphorus to our surface waters. While point sources of P, which are more readily identifiable, are coming under control, background loadings continue to in crease. Tackling diffuse sources of P requires a clear

understanding of the relationship between catchment

characteristics, farming practice and P loss. The objec tive of this study was to derive P export coefficients for one of these characteristics, land cover, and from these be able to predict P loadings from nutrient sources within a catchment to a watercourse. The CORINE (Co-ORdination of INformation on the Environment)

Europe-wide land cover database, which has been

adopted by the whole of Ireland, has been used in

conjunction with a GIS (Geographical Information Sys tem). Using the backward stepwise regression proce dures, with observed P loss as the dependent variable, P export coefficients (kg P/ha/year) were derived for each land cover type. When all sub-catchments were

included, the coefficient for improved grassland was

higher than that for non-improved grassland. However, when the more polluted subcatchments (Fisheries Ecosystem Class 6) were removed from the analysis, the P export coefficient was greater for non-improved grassland than for improved grassland, 0.57 to 0.80 as

opposed to 0.25 to 0.39. This unexpected result may be due to the nature of non-improved grassland; lack of

mixing through ploughing ensures that P remains in the surface layers, poor drainage encourages surface runoff (intensified by slope), and cracking caused by poaching facilitates rapid throughflow.

Grass yield and soil P level in response to different

applications of chemical phosphorus fertiliser H. Tunney1, V. Power2, T. O'Donnell1 and T. Hegarty3 1

Teagasc, Johnstown Castle Research Centre, Wexford, Environmental Protection Agency, Johnstown Castle,

Wexford and Teagasc, Rural Economy Research Centre, 19 Sandymount Avenue, Dublin 4

The aim of the experiment was to estimate the mini mum P requirement for grass under cutting conditions. The results described are for the last 4 years of a

10-year experiment that started in 1986. The experi ment had 10 treatments with five replications (50 plots of 10 m X 4 m) at each of three sites: Clonroche, Johnstown Castle Research Centre and Oak Park Re search Centre. The 10 treatments were 0, 20, 30, 40 kg P/ha/year applied in October or March, 50 kg P/ha/year applied in October, and 100 or 200 kg

P/ha/year applied once only in 1986. Herbage yields were measured three times per year and soil samples were taken in October each year after the third cut but before autumn P application. In each of the 4 years under consideration, the plots that received no fer tiliser P tended to have a lower average yield of dry

matter (DM) than plots that received fertiliser P but in most cases the differences were not statistically signifi cant. There was no significant difference in DM yield between the lowest P treatment (20 kg P) and the

higher P treatments and there was no significant dif ference between spring and autumn P application.

Yields for the high single initial P applications were not significantly higher than from the zero-P treatment. The biggest differences in DM yield were between years and sites. Clonroche had the highest average yield (13 t DM/ha) and Oak Park had the greatest variation (7.6 to 14.0 t DM/ha). The treatments had a

greater influence on soil P level than on grass DM

yield. Soils from the zero-P treatments had the lowest values at about 2 to 3 mg P/I soil or about half the value for the plots receiving the lowest P levels. The

highest P treatments maintained the soil P level at Clonroche and Johnstown Castle over the 10 years but soil P level was approximately halved at Oak Park

where the initial P was very high (5, 11 and 42 mg P/l soil, for Clonroche, Johnstown Castle and Oak Park, respectively).

Could soil biology indicate fertility in low input grass land?

C. Leonard1, G.J. Mullen1, J. Breen1 and N. Culleton2

Department of Life Sciences, University of Limerick and Teagasc, Johnstown Castle Research Centre, Wexford

Biological processes which mineralise nutrients are cru cial for soil fertility where the application of soluble fertiliser is limited. Could soil biology indicate fertility in low input grassland? To answer this, relationships

between farm production and soil characteristics were

explored. Soil samples were taken from 30 low-input grassland farms in Co. Limerick and Co. Clare. Mi crobial presence, respiration and enzyme activities were measured together with soil physical, chemical and farm locational properties. A wide range of results was ob tained for each parameter. Production on 24 of the farms was assessed by interview. To establish a fertility figure, grassland production was reckoned in terms of energy as follows: (A + B - C -

D) per hectare of

grassland [A = livestock production; B = grass sold; C

= purchased fodder; D =

purchased non-grass fodder]. Items were converted into metabolisable energy (ME) equivalents and grassland production expressed as GJ

ME/ha/year. Grassland production ranged from 12 to 65 GJ ME/ha/year. Amongst the measured soil fac tors, pH and urease enzyme activity correlated posi tively while root mass and arginase producing organ isms correlated negatively with grassland production (P < 0.05). Stepwise multiple regression of production

with all factors gave the following equation: Grassland

production (GJ ME/ha/year) = 17.63 - 12,28 (root

mass) + 2.22 (silage production) + 8.7E-02 (arginase enzyme activity) + 4.6E-02 (plant available potassium). It may be noted that the soil biological factors which correlated significantly with fertility form an integral part of the nitrogen cycle. The results suggest that




biological indication of soil fertility is worthy of atten tion in low-input grassland systems.

A study of phosphorus loss in overland flow from

grassland soils with low and high P status I. Kurz1, H. Tunney1 and C. Coxon2 1 Teagasc, Johnstown Castle Research Centre, Wexford and

2Environmental Science Department, Trinity College, Dublin 2

This paper gives some initial results of the P concentra tions in overland flow water from two field sites at Johnstown Castle Research Centre, with low and high soil P levels. The two fields described here are small

plots of the order of 1 ha each. The overland flow water is channelled to collecting tanks where flow rate is continuously monitored and samples for P analyses are collected by automatic samplers. The plots are in

permanent grassland and rotationally grazed by beef animals during the growing season. The high P field (Cowlands) has a Morgan soil test P level of 15 mg P/1 soil and the low P field (Warren) has 4 mg P/1. The

high P field had received a dressing of 30 kg P/ha annually, in addition to nitrogen and potassium fer tiliser, over the past 30 years, while the low P field received only small quantities of fertiliser and has re ceived no P fertiliser over the past 5 years. The results for the first year of the experiment indicate that the

average dissolved reactive P (DRP) concentration is in the region of 10 times higher on the high P site than on the low P site (of the order 1.0 compared with 0.1 mg

P/1, respectively). The DRP concentrations for an overland flow event on the 20 and 21 June 1997 together with the corresponding rainfall also showed much

higher P concentrations (10-fold) in the overland flow from the Cowlands site compared with the Warren site.

The concentrations of DRP in water from the high P site would give an annual overland DRP load of about 1 kg P/ha in an overland flow of 100 mm. The results are in broad agreement with results of other similar studies in Ireland and elsewhere. The soil P level is not the only difference between the two sites, for example, P fertiliser was applied in spring to the high P site only. In addition the grass yield was higher on the high P site and this resulted in more animal traffic on the soil

during grazing and more P in animal manure being excreted.

Comparison of five extractants for available phospho rus in 100 Irish soils H. Tunney1, T. Sims2, R.H. Foy3, N. Luka2 and E.

Byrne1 1 Teagasc, Johnstown Castle Research Centre, Wexford, College of Agricultural Sciences, University of Delaware,

Newark, Delaware, 19717-1303, USA and 2Department of Agricultural and Environmental Sciences, The Queen's University of Belfast, Newforge Lane, Belfast BT9 5PX

The aim was to study the relationship between five common extractants for soil phosphorus and see if they could form a basis for comparing P-fertiliser recom

mendations. The 100 soils for the study were selected, in November 1995, to give a good geographical dis tribution and are representative of the main soil types;

three quarters of them were selected from soils with 0 to 15 mg P/kg soil (Morgan extractant). The soils were

sampled by the agricultural advisor or his representa tive and forwarded to Johnstown Castle Research Cen tre for analyses as a basis for deciding the liming, P and

K fertiliser recommendations. The soils were analysed for Morgan P, Olsen P, Mehlich-1 P, Mehlich-3 P,

water-soluble P, organic matter and pH. There was a

significant linear relationship between the results of the five P tests, however, in general a power function gave a better fit. The best relationship for the power fit

was for Morgan with Mehlich-3 (R2 0.83) and with Olsen (R2 0.81). A similarly good relationship was found between Mehlich-1 and Mehlich-3 (R2 0.80). The weak est relationship was between Mehlich-3 and water (R2 0.49). Overall, Morgan and Mehlich-3 gave the best

relationship with the other tests, whereas water gave the weakest overall relationship. A polynomial function

gave the best fit between Mehlich-1 and Mehlich-3 (R2 0.82). The best relationship with water was obtained with Morgan (R2 0.68), Mehlich-3 (R2 0.65) and Olsen (R2 0.63). These tests may be more suited as environ

mental tests for the soils studied than Mehlich-1 (R2 0.49). For agronomic purposes there is a good relation

ship between three extractants (Mehlich-3, Morgan and Olsen) and the relationships may be a basis for com

paring the P-fertiliser recommendations between Ire land, England and the North East USA. For environ

mental purposes a water extractant may give a better estimate of P loss from soil to water. In this study water

gave a relatively poor relationship with the other ex tractants.

Phosphorus concentrations in grass grown on soils with varying phosphorus levels N. Culleton and J. Murphy, Teagasc, Johnstown Castle Research Centre, Wexford

The fertiliser P recommendations for grassland have been reduced in recent years. The new recommenda tions are based on ensuring optimum grass yields with

minimum P inputs. There is some concern if P concen trations in grass are' adequate to meet the require

ments of lactating cows. This work examined the ef fects of three differing soil P levels (4.7, 2.5, U.O mg/kg soil) on P concentration in herbage, and on milk pro duction. Three herds of 21 cows each rotationally grazed 12 paddocks for each of the three soil P levels. Stocking rate was 25 cows/ha for all three herds. Fifty and 25% of land in each treatment was allocated to first and second cut silage, respectively. Nitrogen was applied at a rate of 230 kg/ha over the grazing season to all three treatments. No P was applied to the low P soil, while

dressings of 12 and 20 kg/ha were applied to the medium and high P soils. Herbage for both grazing and

silage making was analysed for P concentration. Milk

yields, cow weights and infertility data were recorded. Mean P levels in herbage pre-grazing were 0.37 (s.e. 0.03), 0.37 (s.e. 0.04) and 0.41 (s.e. 0.04) mg/kg dry

matter for the low, medium and high P soils, respec tively. High P fertiliser levels and high P soil resulted in a high herbage P concentration (0.33 g/kg) in first-cut

silage. Mean P concentrations (0.24 mg/kg) in second cut silages were not significantly different between treatments. There were no differences in mean milk

yield (5,800 kg/per cow), cow weights at the end of the




grazing season (593 kg), or infertility between treat ments. Cows on the high P soils had significantly higher blood P levels at the end of the grazing season than the cows on the low P soils (1.9 v. 1.6 mm/1).

Effect of a grass break in crop rotations on soil N mineralisation and C02 production CJ. Watson1'2, M.D.B. Allen1, D.L. Easson1-2 and P. Poland1

Agricultural and Enviromnental Science Division, De

partment of Agriculture for Northern Ireland and Faculty of Apiculture and Food Science,The Queen's University of Belfast, Newforge Lane, Belfast BT9 5PX

The current study investigated the effect of a 2-year grass break (GR) compared to an arable break (AR) in

crop rotations where soil N mineralisation and C02 production were measured. Both rotations were under

potatoes in 1995 and under winter wheat in 1996. The AR plots were sown with winter barley in September 1996 whereas the GR plots remained fallow prior to the planting of spring barley in April 1997. Each rota tion had three levels of inputs. Current farming prac tice (CFP) used levels of fertilisers and pesticides com

parable to best commercial practice in Northern Ire land. A low input approach (LIA) used 50% of the

inputs of the CFP treatment and the minimum input system (MIN) used no inorganic fertiliser. The site was located at the Agricultural Research Institute at Hills

borough. Plots were 10 m X 20 m laid out in a ran domised plot design with three replicates. Outside the factorial design an area of permanent grass (no fer tiliser applied) acted as a comparison in each of the three blocks. N mineralisation and C02 production was

measured in the top 15 cm of soil from each of the seven treatments, in short-term aerobic incubations at soil temperature at approximately 2-week intervals from

March 1995 to October 1997. Total N mineralised in the permanent grass swards was significantly lower (P < 0.001) compared to either rotation during the potato growing season. However, rates increased dramatically during the autumn of 1995 and remained high there after. A 2-year grass break in an arable rotation in creased both soil N mineralisation and C02 production compared to an arable break and the effect was still

significant after 3 years. Lowering the level of input had no significant effect on N mineralisation or C02 production.

The influence of nitrogen input on the balance between soil NH^N and NOij~N over 7 years on grazed grass swards

CJ. Watson1-2 and P. Poland1

Agricultural and Environmental Science Division, De

partment of Agriculture for Northern Ireland and 2School of Agriculture and Food Science, The Queen's University of Belfast, Newforge Lane, Belfast BT9 5PX

Mineral N was determined at frequent intervals

throughout the year in the top 5 to 7.5 cm of soil from

grazed grass swards receiving different levels of fer tiliser N input over a 7-year period (1989/90 to

1995/96) at the Agricultural Research Institute of Northern Ireland at Hillsborough, County Down. The

experimental treatments were imposed from March 1989. The treatments were a grass-clover sward receiv

ing no fertiliser N, together with perennial ryegrass swards receiving 100, 200, 300, 400 or 500 kg N/ha/year as calcium ammonium nitrate. The plots were continu

ously grazed by beef steers from April to October to maintain a constant sward height of 7 cm. For the first 3 years, soil samples were taken from the top 5 cm twice a week. In 1992/93, 1993/94 and 1995/96 sam

ples were collected every fortnight in the top 7.5 cm.

Eight cores were removed and bulked together from each of three replicate zones, prior to extraction with 2

M KC1 and mineral N analysis. The average NH4 N and NOJN content (kg N/ha) from 1 March to the end of February was compared for each plot and year. There was little or no change in average soil NO^~N and NH?N content from 1989/90 to 1995/96 on the

grass-clover sward and plots receiving 100 and 200 kg N/ha/year. However, on the plots receiving 300, 400 and 500 kg N/ha/year, NO^"N became progressively

more dominant with time suggesting an increase in net nitrification rate.

Development of a rumen simulation semi-continuous culture

M.C. Hickey1, AP. Moloney1 and M. O'Connell2 1 Teagasc, Grange Research Centre, Dunsany, Co.

Meath and 2Dublin City University, Glasnevin, Dublin 9

The Grange rumen simulation semi-continuous culture (RSSC) is a dual flow system, which concurrently runs four fermentation vessels. The effectiveness of a teflon

junction pH probe to maintain environmental pH between 6.2 and 6.8, over a 10-day period, and the

ability of RSSC to simulate the production of volatile

fatty acids (VFA) were examined. Liquid dilution and solid dilution rates were set at 6 and 3%/h, respec tively. Each vessel was fed daily with 45 g dry matter (DM) at 12 h intervals. All vessels were sampled on

days 6 to 10. Fibre- (F) and starch-based (S) diets, previously fed ad-libitum to cattle, were used. Vessels 1 (VI) and 2 (V2) were fed F, with and without pH control, respectively. Vessels 3 (V3) and 4 (V4) were fed S, with no pH control. Results obtained in vitro for

pH, VFA production and DM digestibility (DMD) for diets F (with and without pH control) and S were

compared with the earlier in vivo results. Addition of

pH control maintained pre-set pH limits, preventing the pH drift (< pH 6) seen in V2, and improved total

VFA production (89 and 83, s.e. 6.6 mmol/1). The in vivo and in vitro diurnal patterns of VFA production differed for both diets. Total VFA production in vivo and in vitro differed for S (105 and 81, s.e 3.9) but not for F (95 , 89 and 83 for in vivo, VI and V2, respec tively). The in vivo and in vitro non-glucogenic ratio did not differ significantly for either diet. In vitro DMD results were lower for both diets when compared to in vivo (570 and 705, and 570 (VI), 580 (V2) and 690 g

DMD for in vitro and in vivo diets, S and F, respec tively). The difference may be attributed to the influ ence of the lower tract and hind-gut fermentation on the in vivo result, while the RSSC simulates rumen




fermentation only. It is concluded that the RSSC suc

cessfully models in vivo rumen digestion function for fibre and starch diets, and for optimum control, an

imposed and continuous pH control system is neces

sary.

Development of gas sampling techniques for baled silage P.D. Forristal1, M.P. Mescall1, P. O'Kiely2 and J J. Lenehan2

Teagasc, Oak Park Research Centre, Carlow and

Teagasc, Grange Research Centre, Dunsany, Co. Meath

To facilitate research on factors influencing mould

growth on baled silage, it is necessary to determine the levels of various gases within bales during the conserva tion period. The objective of the work described here

was to establish techniques which would allow gas sam

ples to be taken, transported and analysed without

interfering with the seal on bales. A bale venting device was modified for use as a gas sampling port. Plastic

disposable syringes and partially evacuated sampling test tubes (vacutainers) were evaluated as suitable gas sampling/storage methods. The consistency of the vac uum in vacutainers was measured by recording the volume of water drawn in under vacuum to 10 vacu tainers. Twelve syringes and 12 vacutainers were filled

with 100% oxygen and recoverable oxygen levels were evaluated 6 h and 14 days later, using a gas chromato

graph. To evaluate sampling via the modified bale vent and sampling at different speeds, samples of carbon dioxide (100%) were taken at both 1 ml/s and 2 ml/s syringe filling rates and C02 content was analysed subsequently. The level of vacuum in the vacutainers

was quite constant with a CV of 1.2% recorded (n = 10). There was a difference (P< 0.001) in the level of 02 measured in the syringes and vacutainers at 6 h and 14

days after filling. The mean 02 levels in the syringes were 98.5% (6 h) and 82.5% (Day 14) compared to vacutainer values of 57.4% (6 h) and 54.8% (Day 14) (s.e.d. = 2.38). The vacutainer data was more variable (CV - 7.3%) than the syringe data (CV - 0.07%). The

sampling technique using the modified bale vent and

disposable syringes proved satisfactory. The slow sam

pling speed gave a higher (P < 0.001) recovery rate of the test gas: 99.2% C02 (1 ml/s) compared to 97.4% (2

ml/s) (s.e.d. = 0.24). It is concluded that the sampling technique developed using a modified bale vent and

disposable syringes was satisfactory.

The effect of weight of herbage per unit area and mechanical conditioning treatments on herbage drying rate J.P. Frost and R.C. Binnie, Agricultural Research Insti tute of Northern Ireland, Hillsborough, Co. Down BT26 6DR

The objective of this experiment was to investigate, in wire mesh trays under field conditions, the influence of

weight of herbage per unit area, conditioning and

pressing treatments on herbage drying rate. In June

1995, herbage cut from a perennial ryegrass sward was allocated to one of the following 12 treatment combi nations in a replicated factorial experiment: uncondi tioned (OC) or conditioned by passing between contra

rotating rollers three (3C) or six (6C) times, placed into

trays at the equivalent of 450 (L; spread) and 900 g dry matter (DM)/m2 (H; rowed-up) then pressed (P) to form a forage mat or left unpressed (OP). Hourly

weighing over an approximately 6-h period enabled the moisture loss from the herbage in each tray to be estimated. The effect of pressing on the rate of mois ture loss was small. Weight of herbage per unit area and conditioning treatments influenced (P < 0.05) the rate of moisture loss. The overall mean final DM con centrations for the L and H treatments were 633 and 308 g DM/kg respectively (s.e. 4.2; P < 0.001). Aver

aged over pressing treatments, the final DM concentra tions for (a) the OCL, 3CL and 6CL treatments were

470, 678 and 716 g DM/kg, respectively, and (b) 291, 317 and 316 g DM/kg for the OCH, 3CH and 6CH treatments, respectively (s.e. 7.3; P < 0.001). It is con cluded that weight of herbage per unit area is the most

important factor influencing the drying rate of herbage and that the greatest increase in the rate of moisture loss was obtained from the least intensive conditioning treatment.

The effect of weight of herbage per unit area and the

proportion of conditioned herbage in the swath on

herbage drying rate R.C. Binnie and J.P. Frost, Agricultural Research Insti tute of Northern Ireland, Hillsborough, Co. Down, BT26 6DR

The objective of this work was to investigate, in wire mesh trays under field conditions, the effect of weight of herbage per unit area and the proportion of condi tioned herbage in the swath on herbage drying rate. In June 1995, herbage cut from a perennial ryegrass sward

was conditioned by passing between contra-rotating rollers or left unconditioned and then allocated to one of 10 treatments in a replicated factorial design experi ment. The treatments were 450 (L; spread) and 900 g dry matter (DM)/m2 (H; rowed-up) and 0, 25, 50, 75 and 100% conditioned herbage in the herbage mass.

Hourly weighing enabled the moisture loss from the

herbage in each tray to be calculated over an approxi mately 6-h period. Weight of herbage per unit area had the greatest effect on drying rate. Final oven DM concentrations were 307, 326, 358, 392, and 409 g

DM/kg, respectively, for 0L, 25L, 50L, 75L and 100L and 204, 216, 217, 230 and 233 g DM/kg for OH, 25H, 50H, 75H and 100H treatments, respectively (s.e. 5.0; P < 0.001). Averaged over all proportion treatments, the final oven DM concentrations for the two weights

of herbage per unit area treatments were 358 and 220 g DM/kg, respectively, for L and H swath density (s.e. 3.2; P < 0.001). It is concluded that weight of herbage per unit area had the greatest influence on herbage drying rate and the proportion of conditioned herbage in the swath was of most benefit for the spread crop.




Vitamin E concentrations in silage samples collected from around Ireland

A. Lynch1, J.P. Kerry1, DJ. Buckley1 and P.A. Morris

sey2 Departments of Food Technology and Nutrition, Uni

versity College, Cork

Grass silage is the most common feed for cattle over wintered indoors in Ireland, but there is little informa tion on the vitamin E levels in such feed. The objective

of this study was to determine the levels of a-tocopherol present in silage. First-, second- and third-cut silage samples were collected from eight counties around Ire land (184 samples in total) and analysed for vitamin E concentration. The concentration of a-tocopherol (/Ag/g wet weight) was determined using a Soxhlet extraction followed by high performance liquid chro

matography analysis (HPLC). A wide variation in a

tocopherol levels was found. The a-tocopherol levels in first-, second- and third-cut silages ranged from 0.4 to 9.2 /Ag/g, 0.4 to 7.8 /xg/g and 0.2 to 1.0 f*g/g, respec tively. The mean values for a-tocopherol concentration in first- second- and third-cut silages were 2.6 ?1.7,

2.3 ? 1.3 and 0.7 ? 0.5 u-g/g, respectively. The county of origin had no significant effect on the a-tocopherol levels, but Donegal had the highest, and Cork had the lowest, a-tocopherol levels. There was no significant difference in vitamin E level between first- and second cut silages, but third-cut silages had less (P < 0.05) vitamin E than the other two cuts.

Effect of dietary vitamin E supplementation on the

qualify of fresh, frozen and vacuum-packaged beef M.P. Lynch3, J.P. Kerry1, DJ. Buckley1 and P.A. Mor

rissey2 Departments of Food Technology and Nutrition, Univer sity College, Cork and ^Department of Animal Science, University of Connecticut, Storrs, CT 06269, USA

Oxymyoglobin (OxyMb), the pigment responsible for the desirable red appearance of meat, may be main tained in meat by delaying the process of pigment oxidation to metmyoglobin (MetMb), the undesirable brown colour associated with discoloured meat. The formation of MetMb from OxyMb appears to be re lated to lipid oxidation and dependent on the antioxi

dant status. The objective of this study was to de termine the effects of dietary vitamin E supplementa tion on tissue a-tocopherol levels in three different

muscles (M. psoas major (PM), M. longissimus dorsi (LD) and M. gluteus medius (GM) and on the suscepti bility of fresh, frozen and vacuum-packaged beef to

lipid oxidation (measured by TBARS) and colour (Hunter values) deterioration. Two groups (n = 5) of Friesian steers were fed diets containing 20 (control) or 2000 (supplemented) lU/head/day a-tocopherol for 50 days prior to slaughter. a-Tocopherol levels were

higher (P < 0.05) in muscles from supplemented ani mals than from controls. There were significant differ ences in a-tocopherol levels between different muscles. In the supplemented groups the order was: PM > LD > GM (P> 0.05), and in the control group the order

was: PM > GM > LD (P > 0.05). Supplemented fresh, frozen and vacuum-packed beef showed greater colour and oxidative stability than beef from the control group after 7 days storage (P < 0.05). Meat samples from LD

was more colour stable and more resistant to lipid oxidation than both PM and GM. Thus, dietary vitamin E supplementation appears to retard MetMb formation and suppress lipid oxidation in LD, GM and PM.

Aerobic stability of whole-crop wheat silage following addition of heterofermentative lactic acid bacteria P. O'Kiely, Teagasc, Grange Research Centre, Dunsany, Co. Meath

To determine the effects of an additive based on the heterofermentative Lactobacillus buchneri on the aer obic stability of whole crop wheat (WCW) silage, chopped samples of three crops were ensiled in labora

tory silos (6 kg WCW/silo; 4 silos/treatment) without additive or after treatment with a bacterial inoculant {.Lactobacillus buchneri, xylanase, galactomannanase, /3-gIucanase, sugar and flow agents; ASW 57; Biotal

Ltd., Wales) applied at 4 ml/kg crop. Silos were stored at 15?C for 120 days. Silage aerobic stability was as sessed during 8 days incubation at 20?C, immediately after silo opening. Mean silage dry matter (DM) con centrations ranged between 346 and 423 g/kg and all

silages made without additive underwent lactic acid dominant fermentations. Averaged over the three crops, additive treatment increased acetic acid (9 to 15 (s.e. 0.09) g/kg DM, P < 0.001) concentration. It reduced the mean concentrations of lactic acid (45 to 35 (s.e. 2.7) g/kg DM; P < 0.05) and water-soluble carbohy drates (24 to 15 (s.e. 1.3) g/kg DM, P < 0.001) and the

yeast count (4.96 to 2.70 (s.e. 0.212) log10 colony forming units/g, P < 0.001). Mould count at silo opening and

recovery rates of ensiled DM were not affected by additive treatment, but silage aerobic stability was im

proved as indicated by the prolonging of the interval to

pH rise (3.8 to 7.7 (s.e. 0.45) days, P < 0.001) and the reduction in the accumulated temperature rise to day 5 (45 to 17 (s.e. 2.9)?C, P < 0.001). It is concluded that additive treatment improved the aerobic stability of fermented WCW silage. This was likely due to the reduced numbers of yeast present in silage at silo

opening, which, in turn, appears associated with a less homolactic fermentation.

Aerobic stability of maize silage following addition of

sulphites at ensiling or feedout P. O'Kiely, Teagasc, Grange Research Centre, Dunsany, Co. Meath

The effects of adding a series of rates of sulphites to

forage maize at ensiling or feedout on silage aerobic

stability were determined. Samples (7 kg) of precision chopped maize were placed in 64 polythene bags, with four bags being allocated (time 0) at random to each of 16 treatments arranged in a 2 (addition of sulphites pre- or post-ensilage) x 2 (0 or 24 h exposure to air

pre-ensiling) X 4 (0, 0.4, 0.8 or 1.2 ml sulphites/kg maize) factorial design. Sulphite (Regulator; Thomas and Fontaine Ltd.) treatments were applied in distilled water at 2 ml/kg maize. Maize (6 kg) was ensiled in

laboratory silos, and stored at 15?C for 239 days, before assessment of aerobic stability at 20?C for up to 10

days. Forage temperatures of 14+TC and 19 + 2?C were recorded at time 0 or after 24 h non-anaerobic




storage, respectively. Delayed sealing of silos resulted in silages of lower lactic-acid concentration and ele

vated acetic-acid concentration. Increasing rates of sul

phite addition reduced the concentration of fermenta tion acids and increased DM digestibility. The aerobic

stability of maize silages as assessed by the accumu lated temperature rise to day 8, for the 0, 0.4, 0.8 and 1.2 ml sulphite/kg treatments, were, respectively, as follows: 0 h ensiling 76, 56, 57 and 58 (s.e. 4.1)?C; 24 h

ensiling 62, 57, 39 and 28 (s.e. 4.1)?C; sulphites applied pre-ensiling 92, 77, 87 and 84 (s.e 4.1)?C and applied post-ensiling 46, 36, 9 and 3 (s.e. 4.1)?C. The aerobic

stability of forage maize silage was significantly im

proved when sulphites were intimately mixed with it at

feedout, but only a small or no effect occurred when

sulphites were applied after harvesting. Forage maize ensiled quickly after harvesting resulted in a higher lactic acid:acetic acid ratio than where achieving anaer

obic conditions was delayed for 24 h, and was associ ated with poorer aerobic stability.

Rumen digestion in steers offered three grass silages supplemented with two levels of concentrates

P. Shiels1'2, P. O'Kiely1, A.P. Moloney1 and PJ. Caf

frey2 Teagasc, Grange Research Centre, Dunsany, Co. Meath

and Faculty of Agriculture, University College Dublin, Belfield, Dublin 4

To determine the effects of silage additive and of

supplementary concentrates on digestion in cattle, un wilted grass of low water-soluble carbohydrate concen tration (19 g/kg aqueous phase) and high buffering capacity (593 mEq/kg dry matter (DM)) was ensiled

without additive (N), with the addition of formic acid (850 g/kg; 2.7 1/t; F) or a lactic-acid bacterial inocu lant (Lactobacillus plantarum; Ecosyl, 3.3 1/t; I). The

silages were offered at 0.9 of ad libitum intake together with 0 or 2.7 kg concentrates per head daily to six Friesian steers in each of two 6 (treatments) x 6 (peri ods) latin square experiments. The N, F and I silages had 169 (s.d. 4.4), 188 (s.d. 9.6) and 172 (s.d. 6.6) g

DM/kg and pH values of 4.4 (s.d. 0.10), 4.0 (s.d. 0.08) and 4.2 (s.d. 0.28), respectively. There were no signifi cant additive X supplementary concentrate interac tions. Neither silage additive nor concentrate supple

mentation affected rumen degradability, rumen liquid pool size or liquid passage rate. Rumen DM pool size was increased (6.4 to 6.8 (s.e. 0.17) kg) by supplementa tion. Silage additive treatment did not alter nitrogen balance, microbial protein synthesis, rumen fluid pH, or concentrations of ammonia, volatile fatty acids or the non-glucogenic ratio in rumen fluid. For N, F and I, respectively, the following values were obtained: blood urea 4.39, 4.59 and 3.96 (s.e. 0.120) mmol/1 (P < 0.01); rumen fluid acetate:propionate 4.07, 3.63 and 3.77 (s.e. 0.125) (P - 0.059); rate of DM passage (Kp) 1.13, 1.27 and 1.18 (s.e. 0.053) %/h (P < 0,01); and rate of DM

digestion (Kd) 330, 3.91 and 3.47 (s.e. 0.147) %/h (P < 0.05). Supplementation with concentrates signifi cantly increased N balance, blood urea, Kp and Kd. It is concluded that formic acid but not inoculant treat

ment improved silage nutritive value under the prevail ing conditions. Improved kinetics of rumen digestion and passage most likely explain the improved intake of

silage DM associated with formic acid.

The potential of silage inoculants with different species and strains of lactic acid bacteria to influence rumen metabolism in steers P. Shiels1'3, P. O'Kiely1, A.P. Moloney1, B. Corcoran2,

M. O'Connell2 and PJ. Caffrey3 1 Teagasc, Grange Research Centre, Dunsany, Co. Meath, Dublin City University, Glasnevin, Dublin 9 and ^Faculty of Agriculture, University College Dublin, Belfield, Dublin 4

Grass of low water-soluble carbohydrate concentration (16 g/kg aqueous phase) and high buffering capacity (527 mEq/kg dry matter (DM)) was ensiled;with (A) no additive, (B) Lactobacillus plantarum (Ecosyl, Zeneca

Bioproducts Ltd.), (C) L. plantarum (DCU 101), (D) Pediococcus spp. (G 24) or (E) L. plantarum (DCU 101) 4- Pediococcus spp. (G 24) to determine their ef fects on rumen metabolism in cattle. Friesian steers

were used in parallel 5 (animals) X 5 (28 day periods) latin square design experiments, with silages offered at

0.9 of ad libitum, supplemented with 1.8 kg concen trates per head daily. All silages were unwilted and underwent similar lactic acid-dominant fermentations, and resulted in similar intakes. There were no treat

ment effects (P > 0.05) on N balance, blood urea con centration or on rumen fluid pH, volatile fatty acid or ammonia concentrations. The following were recorded for cattle offered silages A, B, C, D and E, respectively: rumen fluid acetate to propionate ratio 3.88, 3.S4, 3.84, 4.23 and 4.23 (s.e. 0.105) (P < 0.05); rumen fluid non

glucogenic ratio 4.75, 4.86, 4.86, 5.24, 5.28 (s.e. 0.120) (P =

0.067); average rumen DM pool size 6.35, 6.48, 6.40, 6.27, and 6.18 (s.e. 0.462) kg (P> 0.05); rate of

passage of DM 1.40,1.21,1.37,1.32 and 1.30 (s.e. 0.141) %/h (P > 0.05); and rate of digestion of DM 3.20, 3.52, 3.86, 3.91, 3.55 (s.e. 0.356) %/h (P > 0.05). Silage addi tive treatment did not affect rumen degradability of

DM, neutral detergent fibre or nitrogen. It is con cluded that under the prevailing conditions the additive treatments did not improve silage nutritive value.

Mushroom growths on big-bale silage in Ireland K.C. Brady1, H. Fuller1, D. Forristal2, JJ. Lenehan3 and P. O'Kiely3 ^Department of Botany, University College Dublin,

Belfield, Dublin 4, 2Teagasc, Oak Park Research Centre, Carlow and Teagasc, Grange Research Centre, Dunsany, Co. Meath

In November 1990 and October 1991, mushroom

growths on big-bale silage from Leitrim and from Tip perary, respectively, were identified as Schizophyllum commune. This is a gilled bracket fungus known pri marily as a white rot fungus, found worldwide on fallen branches in woodland. Apart from the mycological in terest in observing this fungus in an unusual niche, the finds attracted no further attention. However, by au tumn 1995 it was evident that Schizophyllum was of

more common occurrence on big-bale silage in Ireland.

During the winter seasons of 1996 and 1997 the fungus was identified in numerous big-bale samples, obtained from all counties. When the plastic covering is removed from a bale affected by Schizophyllum, thick masses of

white to fawn-coloured mycelium are evident on the

silage surface, usually accompanied by dense rubbery




differentiating tissue. Mechanical pressure exerted by the enlarging fungal mass causes a stretching of the

polythene cover and its eventual penetration by the

fungus. Having emerged through the plastic the fungus is first evident as small white growths, which eventually expand and develop into gilled bracket mushrooms, often in clusters or rosettes 10 to 15 cm in diameter.

Apart from one location where Coprinus macrocephalus was present on badly decomposed silage, S. commune was the only mushroom growth found on big bales. It is concluded that Schizophyllum commune grows on big bale silage throughout Ireland, sometimes resulting in considerable loss of feedstuff.

Iodine supplementation of cows and calves via trough water P.A.M. Rogers1, J.F. Mee2 and MJ. Drennan1 1 Teagasc, Grange Research Centre, Dunsany, Co. Meath

and Teagasc, Moorepark Research Centre, Fermoy, Co. Cork

Plasma inorganic iodine (PII) indicates current iodine (I) intake. Two experiments (A, in beef cows and calves, and B in dairy cows) were done to assess the effects on PII in cattle at pasture of I-tablets (Aquadyne, Mayo Healthcare, Westport, Co. Mayo) which supplied 420 mg I/tablet via the trough-water supply. The recom mended 'standard dose' was 1 tablet/7 cows/day, as

suming a cow live weight of 600 kg. The tablets were added daily to a dispenser in the water trough. PII was

measured twice pre-trial, 4 to 5 times on trial and twice

post-trial, after removal of I-tablets. Treatment effect was calculated as the PH-difference between the On Phase (values during medication) minus the Off-Phase (values pre- and post-trial). In the Off-phase of both

experiments, PII remained very low (< 25 /Ag/1) throughout. In A (beef cows and calves), allowing for calf weights, Lim X Fr cows (n = 11) and their calves (n

? 11; 4 month-old) got 1 tablet/14 cows/day for 14

days. Treatment effect (X ? s.e.) of 30 mg I/cow/day was 42.5 ? 3.4 p,g/l in beef cows (P < 0.001) and the same (40.5 ? 8.0 /xg/1) in their suckling calves (P < 0.001). In B (dairy cows), Holstein cows (568 kg) got three treatments (n = 10 cows /treatment) over 28 days: F (1 tablet/7 cows/day), H (1 tablet/14 cows/day), C (unmedicated water). Treatment effect (X ? s.e.) of 0, 30 and 60 mg I/cow/day was 0.4, 35.3 and 75.8 (s.e.m. 9.5) /Ag/1, respectively (P < 0.001). It was concluded that an I-tablet dose of > 60 mg I/cow/day would be needed to maintain PII > 105 /ig/1 (the threshold used at Grange), but 60 mg I/cow/day would suffice to

maintain PII > 70 /Ag/1 (a threshold suggested by other workers).

Effect of concentrate type and feeding method on per formance of cattle offered grass silage based diets

MJ. Drennan and AP. Moloney, Teagasc, Grange Re search Centre, Dunsany, Co. Meath

The objectives of the present experiments were to de termine the effects on grass silage intake and perfor

mance of steers of offering supplements based on bar

ley, wheat or grain screenings (poor quality), and to

compare once and twice daily feeding of supplements.

Four feeding experiments were carried out using 215 steers. The duration of Experiments 1, 2, 3 and 4 were 152, 112, 111 and 113 days, respectively. In each experi

ment silage was available to appetite and the supple ments (6 kg/animal daily) offered were (1) none, (2) barley-based twice daily, (3) barley-based once daily, (4) wheat-based twice daily, (5) wheat-based once daily, and (6) grain screenings-based twice daily.

Minerals/vitamins were offered at 45 g/head daily to animals given silage alone and at 15 g/kg ration for the

remaining groups. At the end of each experiment all animals were slaughtered and carcass weights recorded. Daily carcass weight gains (silage dry matter intakes

kg/day) for Treatments 1, 2, 3 and 4 were 479 (7.84), 829 (5.14), 800 (5.04) and 867 (5.49) s.e.d. 50 g in

Experiment 1; for Treatments 1, 2, 3, 4 and 6 were 386

(6.84), 767 (4.18), 717 (4.05), 757 (4.24) and 546 (4.51) s.e.d. 52 g in Experiment 2; for Treatments 1, 2, 3, 4, 5 and 6 they were 221 (7.00), 584 (4.94), 509 (4.28), 515 (4.12), 520 (4.02) and 494 (5.56) s.e.d. 52 g in Experi

ment 3; for Treatments 2, 3, 4, 5 and 6 they were 486 (4.26), 404 (3.70), 438 (3.63), 434 (3.66) and 257 (5.14) s.e.d. 56 g in Experiment 4, respectively. Feeding 6 kg of a barley-based concentrate daily with silage im

proved carcass gain by 365 g/day. Barley- and wheat based supplements gave similar weight gains but com

pared to a barley-based supplement, animals offered

grain screenings had substantially lower (190 g/day carcass) weight gains. Averaged over all comparisons (four with barley and two with wheat) feeding 6 kg of

supplement in two as opposed to one feed daily non

significantly increased carcass gain by 39 g/day.

The effects of concentrate level and system of herbage allowance on beef production in the autumn P. French1'2, E.G. O'Riordan1, A.P. Moloney1, P.

O'Kiely1, J. Humphreys1 and PJ. Caffrey2 1 Teagasc, Grange Research Centre, Dunsany, Co. Meath


In autumn, grass supply, quality and feeding value decline and supplementing grass with concentrates may be necessary for optimum animal performance. The

objectives of the studies reported here were to de termine the effects of (1) supplementing grazed grass in the autumn with concentrates and (2) managing cattle

offered a similar mean herbage allowance as a single group or as leader and follower groups, on herbage intake and animal performance. Seventy continental crossbred steers (mean live weight 504 kg) were as

signed to seven treatments. In experiment 1, cattle were offered 11 kg grass dry matter (DM) supple mented with either 0, 2.5 or 5 kg concentrates, or concentrates ad libitum (no grass). In experiment 2, three groups of cattle were offered a mean of 11 kg grass DM per head daily in two treatments ? cattle

were managed as a single group or as separate leader and follower groups. Grass allowance was offered daily and concentrates were fed individually. Cattle were

weighed fortnightly and were slaughtered at the end of the 100-day experimental period. Grass intake was esti

mated from the difference between pre- and post-graz ing yields cut to 4 cm stubble height. Supplementation

with concentrates decreased grass intake but, increased final live weight (P < 0.001), carcass weight (P < 0.001),




carcass conformation (P < 0.001), and carcass fatness (P < 0.05). In experiment 2, the leaders had higher (P < 0.001) carcass gains than the single group, but the followers had lower carcass gains (P < 0.001). Overall the leader/follower group had lower carcass gains and

higher grass DM intakes than the single group.

The role of grazed grass in beef production during the winter P. French, E.G. O'Riordan and J. Humphreys, Teagasc, Grange Research Centre, Dunsany Co. Meath

Grazed grass is the cheapest source of feed available for ruminant livestock in Ireland, costing approximately one-third the cost of silage per kg of digestible dry matter (DM). The objective of this study was to de termine the animal performance effects of replacing

part or all of the silage component of the diet in continental yearling cattle with grazed grass. In Jan uary 1997, 36 continental crossbred yearlings were ran

domly assigned to three treatments. The treatments were (1) silage ad libitum plus 3 kg concentrates per head daily, (2) silage ad libitum plus 3.5 kg grass (DM) plus 3 kg of concentrates per head daily and (3) 3.5 kg grass (DM) plus 3 kg of concentrates per head daily. In late September 1996, an area of land was cut for silage and fertilised with 25 kg N/ha. Cattle on treatments 2 and 3 grazed this area from 9 January to 24 March, after which all animals grazed together until slaughter (19 October and 9 November for the heifers and steers,

respectively). Treatment 2 and 3 animals were housed and were let out each day for 3 h to graze an area large enough to provide the target herbage allowance (above 4 cm). Concentrates were offered once daily after the

grazing animals were re-housed. Animals offered grass during the winter had lower live-weight gain (P < 0.001) in winter. However, they fully compensated during the summer with a higher live-weight gain (P < 0.05). Over all there was no effect of winter diet on live-weight gain over the entire experimental period. There was no animal performance advantage in offering a mixture of two forages.

Beef and herbage production from grass/clover swards E.G. O'Riordan1, G. Travers1'2 and P. French1*3, 1 Teagasc, Grange Research Centre, Dunsany, Co. Meath, The Queen's University of Belfast, Newforge Lane, Belfast

BT9 5PX and * Faculty of Agriculture, University College

Dublin, Belfield, Dublin 4

In autumn 1992, half of each replicate subdivision of a

permanent pasture was ploughed and reseeded with a Lolium perenne (Green Isle)/Trifolium repens (Susi) mixture. White clover (Susi) was stitched into the re

maining old sward. In spring 1997, two grazing treat ments were imposed on two pasture types which previ ously (1993 to 1996) had received 50 or 150 to 200 kg inorganic N fertiliser/ha/year. Treatments A and B

represented spring animal stocking rates of 3000 and 2500 kg live weight/ha on old pasture and Treatments

C and D represented the corresponding stocking rates on reseeded swards. Each treatment initially consisted of 12 paddocks in spring and was rotationally grazed. After silage harvesting, the number of paddocks per treatment increased to 19. All swards received 50 kg

N/ha in February. No further N was applied to treat ments B and D during the year, while treatments A and C received approximately 35 kg N/ha after each graz ing cycle. Twenty continental crossbred suckler yearling animals (10 males, 420 kg live weight and 10 females, 365 kg live weight) were used per treatment. Heifers were slaughtered at approximately 18 months (Septem ber, 500 to 550 kg live weight) and steers at 20 months

(November, 600 to 650 kg live weight) of age. Live

weight gains at grass from turnout on 24 March until

slaughter date averaged 0.85, 0.90, 0.87 and 1.01

kg/head/day, for Treatments A, B, C and D, respec tively (P = 0.07), Corresponding carcass weights were

303, 310, 310 and 320 kg (P - 0.09). Steers and heifers had a final carcass weight of 342 and 280 kg, respec tively. Neither pasture type (permanent or reseeded) nor sward type (clover or nitrogen) had an effect on carcass conformation or fat score (P - 0JO).

Effect of regrowth interval and nitrogen application rate on herbage production E.G. O'Riordan, Teagasc, Grange Research Centre, Dun

sany, Co. Meath

Grass dry matter (DM) growth rates (kg DM/ha/day) and total annual production (kg DM/ha) were de termined between February to December on a 5-year old Lolium perenne (cv. Majella) sward. Treatments, consisting of either a 3-week or a 4-week cutting cycle, received an annual fertiliser input of 0, 150, 300 or 450

kg N/ha were cut to a 4 cm stubble height. A 3-week

grazing cycle received an input of 300 kg N/ha was also included where cattle grazed to approximately 4 to 5 cm and was then cut to a stubble height of 4 cm.

Average grass growth rates were determined by divid

ing the DM yield by the number of days growth (i.e. 21 or 28). Total herbage production for the season in

response to receiving 0, 150, 300 or 450 kg N/ha was

5372, 8960, 10,240 and 13,437 kg DM/ha on swards with 3-week regrowth, and 8273, 11,837, 13,695 and 15,793 kg DM/ha on swards with 4-week regrowth, respectively. Both regrowth interval and N application rate had a significant effect (P < 0.001) on herbage production. There was no N X regrowth (interval) inter action. In general, greater production responses were obtained from an extra weeks grass regrowth than from the next increment of N applied. Thus, increasing N

input from 150 to 300 kg N/ha increased yield from 8533 to 9728 kg DM/ha on a 3-week regrowth cycle, but production was increased to 11,209 kg DM/ha when 150 kg N/ha was applied to swards allowed to

grow for a fourth week. A similar observation was made when N was increased from 300 to 450 kg N/ha on a 3-week regrowth compared with a 4-week re

growth receiving 300 kg N/ha. It was concluded that an extra week's regrowth was equivalent to an N appli cation of 150 kg N/ha.




Herbage supply and quality and animal performance on drystock farms S. Devany1*2, E.G. O'Riordan1 and P.J. Caffrey2 Teagasc, Grange Research Centre, Dunsany, Co. Meath


Grassland management and animal performance on 11

drystock farms (22 to 79 ha) were monitored during 1996. Sward height (cm), dry matter (DM) yields and

pasture cover (kg DM/ha) on the grazing area were recorded using a plate meter, once per month, in May, June, November and December, and fortnightly from

July to October. Four DM yield estimates were made on fields where cattle were currently grazing and had last grazed. Representative samples of herbage avail able for grazing were obtained for chemical analyses. Sward botanical composition was determined in au tumn. Cattle weights were recorded at turnout, twice

during the summer and at housing. Mean pasture cover was generally low (< 840 kg DM/ha) from July on wards. At housing pasture covers were low (20 to 460

kg DM/ha). Dry matter digestibility values of grazed herbage in July, August, September and October were 739 ? 32, 751 ? 29, 772 ? 24, and 758 ? 28 g/kg, re

spectively. Botanical analysis showed total tiller counts

ranging from < 10,000 to 14,500 tillers/m2. Lolium perenne proportion varied within each farm and the

range was from 0.29 to 0.77 across all farms. Poa and

Agrostis species accounted for the greatest proportion of remaining species. Live-weight gains for the entire

grazing season were 0.80 ? 0.11 and 0.70 ? 0.14 kg/day for steers and heifers, respectively. Live-weight gain

was highest for both steers and heifers in the early part of the grazing season and decreased thereafter through to housing. In well-managed grazing swards seasonal

changes in digestibility were small.

Effect of summer period at pasture on the performance of young bulls offered concentrates ad libitum R.J. Fallon and B. Earley, Teagasc, Grange Research Centre, Dunsany, Co. Meath

An increase in the availability of Holstein calves in Ireland provides the opportunity to investigate the pro duction potential of red veal with the animals spending some time at grass. In Experiment 1, fifty-four 14

week-old spring-born bull calves (126 kg) were ran

domly allocated to three treatments as follows: (1) indoors on concrete slats throughout, (2) outdoors from 112 days, then indoors on slats, and (3) outdoors for 112 days with restricted concentrate, then indoors on slats with ad libitum access to concentrate. In Experi

ment 2, fifty-four 24-week-old autumn born bull calves (233 kg) were randomly allocated to three treatments as follows: (1) indoors on concrete slats throughout, (2) outdoors for 77 days, then indoors on slats, and (3) outdoors throughout. All animals in both experiments had ad libitum access to a concentrate diet (kg/t) barley (850), soyabean meal (80), molasses (50) miner als plus vitamins (20) with the exception of treatment 3, in Experiment 1. Pen intakes were recorded weekly. A

daily allowance of 50 g straw per kg concentrate intake was provided. Mean (s.e.d.) live-weight gains, carcass

weights, conformation scores, fat scores, concentrate DM intake and feed conversion ratios for the Experi

ment 1 treatments as listed were 1.27, 1.31 and 1.13 (0.093) kg, 237, 237 and 215 (12.7) kg, 1.9, 2.0 and 1.9 (0.04), 3.1, 3.5 and 3.2 (0.2), 1579,1562 and 1143 kg and 5.0, 4.8 and 4.0, respectively. The corresponding values for Experiment 2 were 1.24, 1.23 and 1.31 (0.143) kg, 236, 234 and 243 (4.9) kg, 1.8, 1.7 and 1.7 (0.04), 3.1,3.2 and 2.8 (0.23), 1268, 1141, 1165 kg and 5.7, 5.8 and 5.0. It is concluded that an outdoor period with ad libitum concentrates did not have any adverse effects on per formance.

The effect of post-partum supplementation on the per formance of primiparous suckler cows and their progeny

M. McGee1'2, MJ. Drennan1 and PJ. Caffrey2 lTeagasc, Grange Research Centre, Dunsany, Co. Meath and Faculty of Agriculture, University College Dublin,

Belfield, Dublin 4

First-calving animals have a longer calving interval than adult cows. As nutrition is one of the major factors controlling reproduction, the objective of this study was to determine the effects of feed energy level post partum on the performance of primiparous cows. Fol

lowing parturition (average 27 February), 39 heifers were randomly assigned to one of two feeding levels, namely (1) ad libitum grass silage (in vitro dry matter

digestibility 767 g/kg) only (n = 19) and (2) ad libitum silage plus 2.5 (n - 20) kg of a barley/soyabean (88:7) concentrate per cow daily. The mean duration of the treatments was 52 days until the animals were let to

pasture. Milk yield estimates using the weigh-suckle weigh procedure were obtained from 22 early calving cows. Cows offered silage only, had numerically higher (0.42 kg) silage dry matter intakes (DMI), lower total

DMI (7.61 v. 9.32 kg, P < 0.001), greater live-weight loss from parturition until turnout to pasture (40 v. 16

kg, P < 0.001), lower (P < 0.01) live weight at turnout to

pasture but subsequently greater live-weight gains at

pasture (72 v. 47 kg, P < 0.01) than cows offered the

supplement with silage. Both groups had similar live

weights in autumn. Calves from cows offered supple ment had numerically higher daily gains indoors but daily gain at pasture and pre-weaning was similar for both treatments. Milk yield indoors was higher (7.8 v. 9.0 kg, P < 0.05) for cows offered the supplement than for cows offered silage alone. Calf daily gain was highly correlated with milk yield (0.83, P < 0.01) in the non

supplemented treatment but the correlation was lower in the supplemented treatment (0.54, P = 0.09). In con

clusion, feeding supplements to primiparous cows sig nificantly reduced live-weight loss during the early post-partum or pre-mating period but there was no effect on live weight the following autumn.

Milk yield and calf performance of suckler cows on different grazing systems

M. McGee1*2, MJ. Drennan1 and PJ. Caffrey2 1 Teagasc, Grange Research Centre, Dunsany, Co. Meath


For economic reasons suckler cow nutrition involves mobilisation of cow body reserves in winter and recov




ery on the cheaper produced pasture, the extent, de

pending on grass supply. The objective of this study was to determine the effect of grazing system on cow milk

yield, body reserves deposition and calf performance to

weaning. Data were collected over 2 consecutive years from four, rotationally grazed (commencing mid-April), grassland systems each with 15 spring-calving cows and

progeny. The systems were (1) high stocking rate (SR), high nitrogen (N), two silage cuts; (2) high SR, low N, two silage cuts; (3) low SR, low N, two silage cuts, and (4) low SR, low N, one silage cut. High and low SR and

N were 0.49 and 0.59 ha/cow unit and 239 and 57

kg/ha on the grazing areas, respectively. Calves were weaned on 26 October in year 1 and on 21 September (drought induced grass shortage) in year 2. For systems (1), (2), (3), and (4) in years 1 and 2, cow live-weight gains to weaning were 110, 68,100,145 kg (s.e. 9.0) and 83, 69, 86 and 129 kg (s.e. 8.1); cow condition score

gains (0 to 5) were 0.96, 0.71, 0.85,1.19 units (s.e. 0.147) and 0.67, 0.29, 0.47, 0.90 units (s.e. 0.149); cow milk

yields (weigh-suckle-weigh technique) were 10.5, 9.3, 9.4, 10.1 kg (s.e. 0.55) and 8.3, 7.2, 9.1, 9.5 kg (s.e. 0.47) and calf daily gains were 1188, 1135, 1201, 1240 g (s.e. 33.6) and 1200, 1199, 1314 and 1342 g (s.e. 37.2), re

spectively. A high SR combined with low N resulted in lower cow and calf performance pre-weaning. SR or N level did not significantly affect cow milk yields under normal weather conditions but in drought conditions

high SR reduced milk yields and calf performance. In restricted nutritional environments suckler cows parti tion nutrients towards milk production rather than body reserve deposition.

Effects of time of complete or partial castration on

performance of beef cattle M.G. Keane, Teagasc, Grange Research Centre, Dun

sany, Co. Meath

The normal time of castration of spring-born calves is the following autumn. The effects of complete or par tial castration of spring-born calves in autumn or the

following spring were examined in two experiments. In

experiment 1, 144 animals at pasture in autumn were

assigned to three castration treatments: (1) complete castration immediately, (2) partial castration immedi

ately (right testicle), completed in spring (left testicle), and (3) complete castration in spring. The animals remained at pasture for 55 days, were housed for a

144-day winter and were then turned out to pasture for a 157-day grazing season. In experiment 2, 72 animals

were assigned in autumn to the above castration treat ments. The animals remained at pasture for 23 days, were housed for a 134-day winter and were then turned out to pasture for a 181-day grazing season. The data from the two experiments were combined for analysis.

There were no interactions between experiment and castration treatment. Mean daily weight gains for the first 2 months following autumn castration and for the

period from autumn to spring castration for the treat ments as listed were 649, 720 and 756 (s.e.d. 27.1, P < 0.05) and 535, 599 and 609 (s.e.d. 19.3, P < 0.05) g/day, respectively. Corresponding values for the 2 month period following spring castration and for the

period from spring castration to the end of the experi ment were 999, 854 and 763 (s.e.d. 35.6, P < 0.001) and

960, 897 and 879 (s.e.d. 17.4, P < 0.001) g/day, respec tively. Overall gains from the start to the end of the

experiment were 746, 747 and 746 (s.e.d. 9.3) g/day. It is concluded that castration or partial castration de

pressed performance over the following 2-month pe riod in both autumn and spring. Animals which were entire or partially castrated gained faster in winter than those castrated in autumn but for the entire experi

mental period there was no difference between the castration treatments.

Health status, immunological and haematological pro files of dairy calves B. Earley and R.J. Fallon, Teagasc, Grange Research Centre, Dunsany, Co. Meath

The objective of this study was to determine the extent of association between calf origin, immunoglobulin sta tus and disease incidence in dairy calves. One-hundred and sixty-two male Friesian calves (approx. 7 days of

age) (autumn; n = 41 farm calves; n = 41 mart calves:

spring; n = 30 farm calves; n = 50 mart calves) were

purchased from either marts or local farms. Serum

samples were collected on days 0 (day of arrival), 7 and 14 after arrival. The physiological parameters mea sured were: total white cell (TWC) count, % lympho cytes and haptoglobin (measure of acute phase re

sponse). There was no significant difference in serum ZST units and Ig levels between healthy farm and

mart-purchased dairy calves on day 0. An outbreak of Salmonella typhimurium occurred in the calf unit within 7 days of calf arrival in both autumn and spring. There was a higher incidence of mortality (P = 0.03) among the farm calves (n = 21) compared with the mart calves (n = 11) which was reflected in lower serum IgG! and total Ig levels on day 0 (IgGi mg/ml 19.5 ? 2.6 v. 28.8 ?2.9; total Ig mg/ml 21.9 ?2.86 v. 31.5 ? 3.05). Nasal swabs for respiratory viruses and Mycoplasma bovis were negative. There were no significant differ ences between farm and mart purchased autumn-born Friesian calves on day 0 for TWC counts. Spring-born mart-purchased calves had higher TWC counts than

spring-born farm-purchased calves on day 0 (P < 0.05). By day 7, the TWC count was higher in both the autumn and spring-born farm calves and the % of

lymphocytes was reduced when compared with day 0 values (P __ 0.05). Haptoglobin levels were higher in the

farm-purchased autumn calves than the mart-purchased autumn calves on day 0. It is concluded that the high challenge of infection associated with the Salmonella

typhimurium outbreak was sufficiently intense to mask the difference in health status which otherwise would be expected within the present range of serum Ig con centrations.

The relationship between immunoglobulin deficiency and disease in calves B. Earley and R.J. Fallon, Teagasc, Grange Research Centre, Dunsany, Co. Meath

The interactive effects of serum immunoglobulin defi

ciency and disease on blood and immune characteris tics of dairy calves and suckled calves were investi

gated. Suckled calves were home bred and were ap proximately 28 days of age and consisted of Continen tal X Beef crosses (n = 98). Dairy calves were mart pur




chased and were approximately 28 days of age at ar rival and consisted of Continental X Friesian (n = 111) and Friesian calves (n = 73). Serum samples were col lected on days 0 (day of arrival) and 56 after arrival. Serum immunoglobulins were measured quantitatively by single radial immunodiffusion and additionally by the zinc sulphate turbidity test (ZST). Serum hapto globin (measure of the acute phase response) was de termined on completion of the study (day 56). Serum

IgGt and total Ig levels were higher (P < 0.01) in the Continental X beef calves at day 0 compared with the Continental X Friesian and Friesian calves. There was no disease outbreak in the suckled calves. Continental X Friesian calves (n = 68) treated for respiratory dis ease had lower (P < 0.04) total Ig (20.8 ? 1.26 v. 24.6 + 1.06 mg/ml ) serum levels on day 0 when compared

with healthy (n ? 43) Continental X Friesian calves. Friesian calves treated for respiratory disease (n

? 56)

had lower (P < 0.03) total Ig (19.5 ? 1.14 v. 24.0 ? 1.48

mg/ml ) serum levels on day 0 when compared with

healthy (n ? 15) Friesian calves. By day 56, haptoglobin levels were higher (P < 0.01) in Continental x Friesian (0.354 + 0.030 v. 0.077 ?0.028) and Friesian calves (0.406 ? 0.036) treated for respiratory disease than in

corresponding healthy Friesian calves. Healthy calves had considerably higher serum immunoglobulins (Ig) than calves treated for respiratory disease. It is con cluded that calves with low immunoglobulins (< 11 ZST units; < 21 total Ig) were more susceptible to

respiratory disease.

Effects of Yucca Schidigera extract on production and

reproduction parameters in cattle and sheep J. Fahey1, M.P. Boland2 and D. O'Callaghan1

Faculty of Veterinary Medicine and Agriculture, Univer

sity College Dublin, Belfield, Dublin 4

Yucca Schidigera extract (YE; Deodorase, Alltech, Ire land) can alter volatile fatty acid production rates in

ovine rumen fluid in-vitro. The objective was to de termine if YE can improve production efficiency in

dairy cows, cattle and sheep in-vivo. In experiment 1, cows were supplemented with 0 g/day (n = 19) or 2

g/day (n = 21) of YE. There were no significant dif ferences (mean ? s.e.) in milk yield (29.2 ? 1.1 v. 28.3 ? 0.8 kg/day), pregnancy rate (14/19 (74% v. 15/21 (71%)) or days open (102.8 ? 10.4 v. 90.3 ? 10.9) between control and YE-treated cows, respectively. However, first service conception rate (4/19 (21%) v.

9/21 (43%), P < 0.1) was higher and services per con

ception (2.14 ? 0.3 v. L5 ? 0.2; P < 0.02) was lower in YE-treated cows. In experiment 2, growth rate of beef heifers, when supplemented with 0 g (n = 16) or 2

g/day (n-16) of YE, was examined. There were no

significant differences in average daily gain (0.6 ? 0.1 v. 0,7 ?0,1 kg/day) or carcass weight after 112 days of treatment (308 ? 8.9 v. 309 ? 8.8 kg) between control and YE-treated heifers, respectively. In experiment 3, the effect of YE on growth and feed conversion effi

ciency of female lambs was examined. Lambs were

supplemented with 0 mg (n = 31) or 250 mg (n ? 32) of YE per day. There were no differences in average daily gain (254.5 ? 11.6 g/day v. 267.1 ? 11.3 g/day) or feed conversion efficiency (kg feed/kg gain; 5.8 ? 0.2 v. 6.2 ? 0.7) between control and YE-treated lambs, respec tively. In conclusion YE did not affect milk yield in cows or growth or feed conversion efficiency in cattle

or sheep, but improved dairy cow fertility, mainly by reducing services per conception and increasing first service conception rate.

The effect of supplementary protein offered to ewes 6 weeks prior to lambing in colostrum production and lamb output

A.F. Carson and L.E.R. Dawson, Agricultural Research Institute of Northern Ireland, Hillsborough, Co. Down BT26 6DF

An experiment was carried out to determine the effect of level and source of protein offered to ewes in late

pregnancy on subsequent colostrum production and lamb performance. Twin-bearing Greyface ewes were offered grass silage and one of six concentrate treat ments for a period of 6 weeks prior to lambing. The concentrations were formulated to provide increasing levels of digestible undegradabie protein (DUP) from

approximately 18 to 66 g DUP/kg dry matter (DM). The DUP was supplied in the form of soypass or fishmeal. Silage and concentrate DM intakes were recorded daily throughout the experiment and the ewes

were weighed at 6 weeks prior to lambing and at

lambing. Jugular blood samples were taken from the ewes at 6, 4 and 2 weeks prior to lambing and analysed for betahydroxybutyrate, non-esterified fatty acids and urea. Colostrum yield was determined at 1, 10 and 18 h

post-lambing. The lambs were weighed at birth and at

regular intervals until weaning. Protein source and DUP content of the concentrate had no effect (P > 0.05) on

any of the parameters measured. However, there was a

tendency for total protein yield of the colostrum to inccrease with increasing DUP content of the concen trate (P - 0.14). The results of this study indicate that

protein source i.e. soypass v. fishmeal or level of DUP in the concentrate had no significant effect on ewe

performance, in terms of colostrum production or lamb birth weight. However, the results suggest that total crude protein yield of the colostrum tends to increase

with increasing DUP content of the concentrate.

The digestibility of protein sources used in ruminant diets FJ. Mulligan, F.R O'Mara, E.J. Cronin, MJ. Kenny,

M. Rath, PJ. Caffrey, J. Callan and B, Flynn, Faculty of Agriculture, University College Dublin, Lyons Research Farm, Newcastle, Co. Dublin

The use of soyabean meal (SBM) as a protein soruce is an expensive option. This has led to the use of other

protein sources in ruminant diets. The objectives of the work carried out was to evaluate three of these protein sources ? cottonseed meal (CSM), rapeseed meal (RSM) and sunflower seed meal (SSM)

? in terms of

composition and digestibility relative to SBM. Four wether lambs (Suffolk or Texel cross) were used to determine the digestibility of each feed ingredient sam

ple. The daily allocation of feed was 800 g/day in total, which consisted of the protein source (300 to 680 g/ day), hay (120 to 250 g/day) and in some cases beet

pulp (0 to 250 g/day). The number of samples (n) used was 8, 4, 6 and 8 for SBM, CSM, RSM and SSM, respectively. The feed closest in crude protein (CP)




content to SBM was CSM (CP: 524, 415, 393 and 319

g/kg dry matter (DM) for SBM, CSM, RSM and SSM, respectively. Although CSM had a high CP content, the

samples exhibited a lot of variation with regard to this

parameter (CV: 2.3, 15.2, 13.2 and 3.3% for SBM, CSM, SSM and RSM, respectively. This variable trend was evident throughout the chemical composition for CSM. Soyabean meal was the most digestible feed (OMD; 917, 689, 585 and 731; s.e.m. 4.6, 7.8, 13.3 and 6.7 for SBM, CSM, SSM and RSM, respectively). The variable nature observed in the composition of CSM was mirrored in its organic matter digestibility (OMD) (CV: 0.8, 8.0, 7.1 and 4.2% for SBM, CSM, SSM and RSM, respectively). There were significant differences (P < 0.05) in OMD between samples of the same feed

ingredient for CSM, RSM and SSM but not for SBM. SBM was higher (P < 0.05) in OMD than RSM, CSM or SSM. Although individual CSM samples had higher OMD and CP values than RSM a higher degree of variation was associated with CSM. The SSM was the

poorest of the protein sources examined in both CP content and digestiblity.

Effect of creep feeding spring-born Iambs set stocked at two sward heights

EJ. Grennan, Teagasc, Research Centre, Athenry, Co.

Galway

In spring lambing flocks producing mid-season lamb a

high lamb growth rate on pasture alone without creep feeding is desirable for economic reasons. The objec tive of this experiment was to investigate the response to creep feeding lambs set stocked on pasture, at two sward heights, from birth to weaning at 14 weeks of

age. Four core groups of March lambing ewes (n = 15) and their lambs (n = 25) were set stocked on pasture from birth to weaning in each of 3 years. Extra dry ewes were added to two groups to maintain two differ ent sward heights. Creep feed, introduced at 3 weeks, was offered at 250 g/day to one group of lambs at each sward height from 5 to 14 weeks of age (total 17 kg). Two-year-old ewes were used in year 1 and grazed old permanent pasture while older ewes were used in years 2 and 3 and grazed a mainly Lolium perenne pasture.

Mean sward heights achieved over 3 years were 6.1 and 4.6 cm for the high and low swards, respectively. Lamb

weaning weights were better on the higher sward, the

average difference being 2 kg with or without creep feed. There was a response to creep feeding Iambs each year at each sward height. The extra live weight at

weaning averaged 3.9 kg at each height, giving a feed conversion rate of 4.4 for the concentrate supplement. It is concluded that in a set-stocking system of grazing lamb growth rate to weaning is affected by sward height and creep feeding.

Lamb performance in a late-lambing system EJ Grennan, Teagasc, Research Centre, Athenry, Co.

Galway

Changing the lambing date from March to April/May is sometimes considered with a view to reducing ewe feed costs, or extending the season for quality younger lamb. A farmlet system was operated with 52 ewes on 4

ha of pasture, (six paddocks), in an all-grass production system. Ewes were mated at pasture to lamb 30 April.

They were inwintered on silage from 7 January to 10 March when they were turned out to pasture 7 weeks

pre-Iambing. No concentrates were offered to ewes

pre-lambing. One silage cut on 35% of the area pro vided silage for wintering ewes and finishing lambs. Ewes (plus 1.65 lambs per ewe) were stocked at 20/ha from lambing until late June and thereafter at 13/ha until weaning at 14 weeks on 7 August. Weaned lambs

grazed ahead of ewes until 14 October when they were housed and finished on silage with concentrate supple

ment. Lamb weaning weight, 26.5 kg, was lower than for normal spring lambing, due mainly to the low growth rate (205 g/day) in the period 5 to 14 weeks of age.

Growth rate of weaned lambs on pasture was 152

g/day up to housing. No lambs were drafted off pas ture and they weighed 35.3 kg at housing. Lambs were drafted in three groups: 33% on 1 December, 17% on 12 December and 50% on 12 January at mean carcass

weights of 19.6, 17.9 and 17.9 kg, respectively. Concen trates consumed by finishing lambs were 20, 27 and 44

kg for groups 1, 2 and 3, respectively, with an average of 33 kg per lamb. It is concluded that late lambing can

give acceptable results but high quality pasture is es sential to achieve high lamb growth rates and reduce the concentrates required for finishing lambs.

Relationship between sward height and herbage dry matter yields E.G. O'Riordan, Teagasc, Grange Research Centre, D?? sany, Co. Meath

Sward height was measured at weekly intervals between

April and November during 5 years using plate meters, and compared to simultaneously measured pasture yields. During 1992 to 1994 the plate meter used ex erted a pressure of 2.8 kg/m2 while that used in 1996 and 1997 exerted a pressure of 3.2 kg/m2. Grass was cut to a stubble height of 4 cm using a reciprocating mower (AgriaX Cutting regimes which were laid out in a randomised complete block design (5 x 2 m per plot), were replicated 4 or 5 times. Sward height measure ments were the mean of 10 individual heights per plot. Grazing plots (6 X 10 m) had yield estimations made similarly to the cutting plots. Swards were typically yielded at 3 to 4 weeks stage of regrowth. During 1997, the collection of data relating to height and yield was extended to 11 commercial farms, where 0.25 m2 quadrats were used to estimate yield to a stubble height of 4 cm. Regression equations between sward height (x, in cm) and herbage dry matter (DM) yields (y, in

kg/ha) showed that linear expressions accounted for 72 to 87% of the variation during the first 3 years. The linear expression, y

= 169(x) ?

410, for the first 3 years combined accounted for 76.5% of variation. A pre harvesting sward height of 5, 10, 15 or 20 cm repre sented yields of 280, 338, 451 or 281 and 1096, 1263, 1466 or 1280 and 1936, 2188, 2481 or 2125 and 2765, 3113, 3496 or 2970 kg DM/ha for the years 1992,1993, 1994 and 1996, respectively. The regression constants

were -575, -587, -564 and -410, respectively. A unit cm change in sward height resulted in a change in

yield of 167, 185, 203 and 169 kg DM/ha for the

respective years. Using the 1996 predictive equation, data collected from two validation experiments in 1997,




showed 85 to 98% of the variation was explained by the

height to yield relationship. It was concluded that a

plate meter could be used as a grassland measured tool.

The effects of concentrate carbohydrate source and

herbage allowance on steer performance in the autumn P. French1'2, E.G. O'Riordan1, A.P. Moloney1, P.

O'Kiely1 and PJ. Caffrey2 Teagasc, Grange Research Centre, Dunsany, Co. Meath


In autumn, grass supply, quality and feeding value decline and supplementing grass with concentrates may be necessary for optimum animal performance. The

objective of this study was to determine the effects of

supplementing cattle with concentrates, formulated us

ing different carbohydrate types, on grass intake and animal performance where grass supply was either ade

quate or limiting. Eighty-four continental steers (494 kg) were randomly assigned to seven treatments in autumn 1997. The experimental design was a two

herbage allowances (5.5 and 11 kg dry matter (DM) per head daily) by three concentrate carbohydrate sources

(starch, starch/fibre and fibre) factorial with a positive control offered concentrates ad libitum. Concentrates were formulated to be iso-energetic and iso-nitroge nous. Grass allowance was offered daily and concen trates were fed individually. Cattle were weighed fort

nightly and were slaughtered at the end of the 85-day experimental period. Six rumen fistulated steers were used in a latin square design to determine the effect of the diets on rumen kinetics. Increasing herbage al lowance increased grass intake and increased (P < 0.001) carcass gain. Increasing concentrate starch con tent increased (P < 0.001) live-weight gain but did not increase carcass weight due to a poorer kill-out rate.

Concentrate carbohydrate source did not affect rumen fluid pH value. There was no interaction between con centrate carbohydrate source and herbage allowance on carcass gain. Cattle fed the starch concentrate pro duced carcasses with lower fat scores (P = 0.087) and lower proportions of internal fat (P < 0.01).

The effect of nitrogen fertiliser and herbage mass on the intake of grazed grass J. Humphreys, E.G. O'Riordan, P. O'Kiely and P. French, Teagasc, Grange Research Centre, Dunsany, Co.

Meath

The accumulation of grass dry matter is inversely re lated to the frequency of defoliation and positively related to applied nitrogen (N). The objective of the

present experiment was to investigate the effect of

pre-grazing herbage mass and N fertilisation on the utilisation of grass by grazing animals. This experiment included three N application levels (100, 250 and 400

kg N/ha) and four target pre-grazing herbage masses

(1000, 2000, 3000 and 4000 kg/ha) arranged in a ran domised complete block design replicated four times. Heifers (350 to 500 kg live weight) were assigned at random to plots, receiving a herbage allowance (availa ble herbage dry matter above 4 cm) of approximately

2% of live weight per 24 h, for a pre-determined time

period of between 24 and 48 h. Plots were repeatedly grazed between early April and late October 1997.

Herbage mass was measured pre- and post-grazing. The difference between these two measurements was taken as the level of intake achieved. Increasing fer tiliser N applications above 100 kg N/ha had little

impact on total season yield of dry matter intake. In

creasing the pre-grazing herbage mass substantially in creased the total season yield of dry matter intake (from 10.4 to 16,0 t/ha). Percentage utilisation of

herbage was also increased by increasing pre-grazing herbage mass (from 50 to 76%), but the relationship was significantly (P < 0.001) affected by an interaction with N application level. At the lower herbage masses,

increasing N application level reduced percentage utili sation, whereas at the highest herbage mass, N applica tion level had no detectable effect on percentage utili sation.

Influence of winter concentrate level and date to pas ture on the performance of previously suckled wean

lings S. Kyne1*2, MJ. Drennan1 and PJ. Caffrey2 Teagasc, Grange Research Centre, Dunsany, Co. Meath and Faculty of Agriculture, University College Dublin,

Belfield, Dublin 4

Cost savings can be made in beef production by avail

ing of compensatory growth and by a reduction in the winter housing period by earlier turnout to grass in the

spring. The objective of this study was to examine the effects of two concentrate levels ((0.5 (low) and 1.5

(high) kg/day)) with grass silage in winter and two turnout dates (21 March and 11 April) on the perfor

mance of 8-month-old spring-born continental cross

weanlings. Animals on the early turnout treatment

grazed the intended silage area until 11 April after which all animals grazed together. Sixty-eight animals

consisting of 40 steers and 28 heifers weighing 333 (s.e. 6.3) and 306 (s.e. 4,6) kg, respectively, were used. Silage intakes were 4.7 and 4.4 (s.e. 0.16) kg dry

matter/head/day for the low and high concentrate

level, respectively. Mean (steer and heifer) winter live

weight gains were 69 and 89 (s.e. 3.6) kg (P < 0.01) for those on the low and high planes, respectively. Corre

sponding summer gains were 193 and 177 (s.e. 4.4) kg (P < 0.05). Early turnout significantly increased summer and total gains of steers (P < 0.05) but had no effect on

live-weight gains of heifers. Combined summer plus winter gains were 271 and 257 (s.e. 4.5) kg for the early and late turnout treatments, respectively (P < 0.05).

When slaughtered at the end of the grazing season there were no treatment effects on carcass weights or carcass traits of heifers. Grazing of the intended silage area significantly reduced (P < 0.01) grass yields in early (14 to 20 May) cut silage plots but had no significant effect on those cut later (3 to 6 June). In conclusion,

feeding concentrates to achieve live-weight gains in excess of 0,55 kg/day in winter while increasing winter

gains will not result in higher overall performance, due to compensatory growth, but extra live weight can be achieved by earlier turnout.




The effects of grazed grass or concentrate diets on

performance and carcass composition of beef cattle N.P. Lavery1 and R.WJ. Steen1'2 Agricultural Research Institute of Northern Ireland, Hills

borough, Co. Down BT26 6DR and 2The Queen's Univer

sity of Belfast, Newforge Lane, Belfast BT9 5PX

Two comparative slaughter experiments involving heifers (El) and steers (E2) were carried out to com

pare grazed grass and concentrate diets in terms of

performance and carcass composition. Fifty heifers and 65 steers, initially 406 kg and 456 kg live weight, were used in El and E2, respectively. The four treatments used in both experiments were: 0.95 concentrates plus 0.05 barley straw, on a dry matter basis, offered ad libitum, (CA), diet CA offered at 86% of ad libitum intake, (CB), diet CA offered at 73% of ad libitum intake, (CO and grazed grass at a target sward surface

height 10 cm, (GG). Linear regression relationships between carcass gain and dry matter intake per kg metabolic body weight (MDMI) and between MDMI and carcass fat classification, non-carcass fat weight, subcutaneous fat depth, marbling score and carcass fat concentration (CFC), for the three concentrate treat

ments, were produced. This enabled values to be pre dicted for concentrate-fed animals at the same carcass

gain as the grazing animals (0.64 and 0.65 kg/day for heifers and steers, respectively). Comparison of the two diet types showed no significant effect on carcass fat classification, non-carcass fat weight, subcutaneous fat

depth or marbling score. The predicted CFC in concen trate-fed animals with a carcass gain equivalent to that of animals on the grazing treatment was 202 g/kg compared to an actual value of 187 g/kg (s.e. 11.1) for the heifers, and 215 g/kg compared to an actual value of 197 g/kg (s.e. 9.7) for the steers. When the data from both experiments were combined the predicted carcass fat concentration (209 g/kg) was significantly greater (P < 0.05) than the actual value (193 g/kg) (s.e. 7.2) obtained for the grazing treatments. It is con cluded that, at equal levels of performance, cattle fin ished off grass had a significantly lower estimated car cass fat concentration than cattle finished on a concen trate diet.

Compositional analysis of carcass dissection data D. Muldowney1, J. Connolly1 and M.G. Keane2

lDepartment of Statistics, University College Dublin, Belfield, Dublin 4 and Teagasc, Grange Research Centre, Dunsany, Co. Meath

Changes in the body composition of animals during development are generally studied using allometric re

gression, modelling the weight (w,) of the /th compo nent as logdvj)

= a{ + bj log(w) where w is the weight

of the whole. Difficulties with this analysis are (i) pre dicted proportions for the components will not neces

sarily sum to 1 and (ii) are not bounded to lie between 0 and 1. This study explored methods, based on compo sitional analysis, which avoid these difficulties. Let xt

=

wt/w for i = l,...,d (d - number of components) rep resent the proportions of some whole. Create d-1 vari ables yly... jV^-i using the transformation y^

=

loge(*,/*_i). Analysis is performed using these y vari

ables. Predictions (yf) are back transformed to the

proportional (x) scale using xê^/ie^1 + ... +e^-J + 1) and xd= 1 ?

?j + ...xdî. The model fitted on the y scale was y-t

= #j + bt loge(w). More complex mod

els, including the effects of factors, can be fitted. Here

ty measures differentiation between the ith and the dth component, with the ith component increasing (for bt >

0) or decreasing (??,-< 0) relative to the dth component as w increases. Predicted component proportions will lie between 0 and 1 and will sum to 1. This approach

was applied to data from the dissection of pistolas from 120 beef carcasses representing three breed types (Friesian, Piedmontese X Friesian and Romagnola X

Friesian) finished on two dietary energy levels. Nega tive coefficients for the muscle/fat and bone/fat ratios (-0.333 and ?0.604, respectively) indicate that these ratios declined with increasing pistola weight, while the

positive coefficient for the muscle/bone ratio (0.271) indicates an increase in the muscle/bone ratio as pis tola weight increased.

Physical and financial performance of sheep flocks: variation within and among years J.P. Hanrahan, Teagasc, Research Centre, Athenry, Co.

Galway

A consistent feature of the results from the annual National Farm Survey (NFS) conducted by Teagasc is the wide variation among farms in both physical and financial performance of sheep enterprises. The objec tives of this study were to quantify the consistency, between years, of differences among flocks and to esti mate the impact of key physical performance factors on

gross margin per ewe. Information on individual farms with a lowland sheep enterprise was extracted from the NFS files for the years 1993 to 1996. Gross margin per ewe (GM) was calculated net of all direct payments. Data were analysed using least squares and maximum likelihood procedures. Overall mean values (range among years) were: ?30.6 (30.1 to 36.6) for GM, 1.40 (1.38 to 1.44) for lambs born per ewe joined (LB), 1.28 (1.24 to 1.30) for lambs weaned per ewe joined (LW), 9.6 (9.3 to 9.7) for stocking rate (SR; ewes/ha), ?43.1 (40.1 to 49.7) for lamb sale price (LP) and ?7.6 (7.3 to 7.9) for ewe replacement cost (RC). The CVs, based on

within-year variation among flocks, were 47%, 15% 17%, 7%, 14% and 54% for GM, LB, LW, SR, LP and

RC, respectively. Multiple regression analysis of GM with LW, SR, LP and RC as dependent variables yielded regression coefficients of 32, 0.5, 0.9 and - 1.1 per unit

change in LW, SR, LP and RC, respectively. All of these were statistically significant (P < 0.05) except for SR. Variance components for permanent flock effects

yielded repeatabilities of 0.52, 0.41, 0.46, 0.83 and 0.61 for GM, LB, LW, SR and LP, respectively. The mean values for the bottom and top quartiles, based on the

permanent flock effects variance were ?17.1 and ?44.1, L23 and 1.57, 1.08 and 1.44 for GM, LB and LW, respectively. The corresponding quartiles for GM ad

justed for variation in LW, SR, LP and RC were ?20.2 and ?40.4. Further investigations are required to iden

tify the causes of wide variation and inconsistency of financial performance.




The effect of dietary intake level and protein content on the true and apparent digestibility of hay FJ. Mulligan, F.P. O'Mara, M.J. Kenny, M. Rath, PJ.

Caffrey, J. Callan and B. Flynn, Faculty of Agriculture, University College Dublin, Lyons Research Farm, Newcas tle, Co. Dublin

The digestiblity of concentrate feedstuffs has been de termined using hay as the basal forage at Lyons Re search Farm for some years now. The digestibility of this hay is assumed to remain unchanged in cases

where the intake of hay and the crude protein (CP) content of the diet have changed. The objective of this

experiment was to examine the effect of both variables on hay digestibility. Twenty-eight wether lambs

(4/treatment) were fed three levels (600, 700 and 800

g/day) of hay, each of two CP contents (100 and 180 g CP/kg dry matter (DM), achieved by spraying on a solution of urea before feeding. An extra group of lambs were fed hay, unsupplemented with urea, (40 g

CP/kg DM) at a level of 800 g/day. The apparent organic matter digestibility (OMD) and true OMD (calculated using two methods, OMD-F and OMD-M) of all treatments fed the 180 g CP/kg DM diets were

higher (P < 0.05) than the apparent OMD and true OMD of all treatments fed the 100 g CP/kg DM diet (OMD 632.8 v. 604.2 g/kg, OMD-F: 720.6 v. 694.1

g/kg, OMD-M: 711.8 v. 681.0 g/kg). For the three

groups fed 800 g/day of hay, regression of OMD and true OMD (F and M) on dietary CP content resulted in

significant relationships being established (P = 0.037, 0.016 and 0.043; s.e. for regression lines =

21.68, 22.01 and 22.89 for OMD, OMD-F and OMD-M). Apparent and true digestibility increased slightly as intake in creased but none of the differences were significant (P < 0.05). It would appear that dietary CP content but not level of intake significantly affected the true and

apparent digestibility of hay.

Behaviour of sheep grazing in a developing silvopas toral system

M. Healy1, J.H. McAdam1, G.M. Hoppe2 and S. Wat son2 1 Department of Applied Science, The Queen's University

of Belfast and Department of Agriculture for Northern Ireland, Newforge Lane, Belfast BT9 5PX

The practice of silvopastoralism, whereby animals are

grazed between widely spaced trees has implications for both animal welfare and tree development. The

grazing and resting behaviour of sheep in relation to

planting density was monitored on three replicates of trees planted into ryegrass dominant pasture as follows:

Sycamore and Ash at 400 stems/ha, Sycamore at 100

stems/ha and an agricultural control (no trees). Each

plot (mean area = 0.55 ha) was grazed with eight ewes. Observations were carried out over the day to record

sheep activity and weather variable at 20 min intervals with a total of 9,405 individual animal observations recorded. Animal activity was shown to be modified by the presence of trees. Sheep in the widely spaced agro forestry treatment behaved in a similar fashion to the

agricultural control, with animals in the closely spaced agroforestry plots spending 4 to 6% less time grazing than in the open plots and the inverse being the case for the resting activity. Activities which directly affect

the trees such as scratching and nibbling occurred most

frequently in the T100 Sycamore treatment due to the

higher sheep:tree ratio in these plots. The mean dis tance of each individual to the nearest tree (3.4, 1.8 and 1.7 m for the T100, T400 Sycamore and T400 Ash, respectively) further illustrated the animal-tree interac tions. Sheep were located closer to the trees when

resting than when grazing and both activities were carried out, on average, closer to the trees than would be the case if their behaviour was unaffected by the trees.

Comparison of overwintering and spring growth of Huia and Aberherald white clover cultivars T Nolan1, J Connolly2, A. Ryan1 and M.L. Reilly2

Teagasc, Research Centre, Athenry, Co. Galway and

Ûniversity College Dublin, Belfield, Dublin 4

The experiment compared the relative abilities of cv. Huia and cv. Aberherald white clovers to survive rela

tively cold wet winter conditions and to compete with

subsequent grass growth. Each clover was grown with Everest and Hercules ryegrasses in a 4 X 4 latin square design. Nitrogen fertilisation was 25 kg/ha at sowing, at beginning of spring growth and after each cut. Soil

phosphorus and potassium levels were 10 and 240 ml/1. Periodically during winter, four sods per plot, each of 12 cm diameter and 10 cm depth were randomly taken.

Plant morphology and carbohydrate contents of stolons were measured on sods and growing season yield from cuts taken each time grass height was 20 cm. A com bined analysis of results is presented, for 1995/96 and

1996/97 seasons, for some morphological characteris tics and for stolon chemical analyses for 1995/96. For sods, the main results were decreases in stolon length, stolon dry weight and number of terminal buds (Huia 44% and Aberherald 70%) from 1995/96 to 1996/97. Stolon weight per unit length was significantly higher for Aberherald with both grasses in 1995/96 and for

Aberherald with Hercules in 1996/97. Clover root dry mass (g/m2 of land area) was significantly higher in

1995/96 than in 1996/97 (29.9 v, 19.0), for Huia than Aberherald (28.9 v. 20.0) and for both clovers with Everest (28.6 v. 20.3). Huia, generally, had a higher percentage contribution to total biomass than Aberher ald (9.9 v. 6.4 in 1995/96; 4.6 v. 1.8 in 1996/97), significantly so overall (P < 0.023). No significant ef fects were observed for grass or weeds as percentages of biomass for cutting and overall. There was a signifi cant difference (P < 0.001) in total non-structural car

bohydrates between Huia (17.90%) and Aberherald (21.02%) but none between clovers with Everest or

Hercules (19.57% v. 19.35%).

Land spreading of spent mushroom compost in Co. Monaghan CA McMahon and G.J. Mullen, Department of Life Sciences, University of Limerick, Limerick

Almost one-third of the Irish mushroom industry is located in Monaghan and 50% of the spent mushroom

compost (SMC) produced is dumped, which is a cause of concern to environmentalists. Because of this, two

experiments were set up to examine the effects of SMC




fiMiciuJmcnt to grassland on soil properties and grass growth. In Experiment 1, SMC was applied in spring at rules of 0, 16.5 and 49.5 t/ha to plots of permanent grassland on a reclaimed gley soil in Monaghan. Three

ages of SMC were used; fresh, aged for 6 months and

aged for 12 months. Herbage dry matter (DM) yield was measured over the growing season, at the end of which soil was removed from all plots for physical and chemical analysis. In Experiment 2, SMC of the ages used in Experiment 1 was incorporated in pots with surface soil from three areas of contrasting soil type and land use in Co. Monaghan at a rate of 49.5 t/ha. Pots were sown with perennial ryegrass. After 8 months, herbage DM yield, plant-available phosphorus (P), pH, electrical conductivity and bulk density were recorded. In Experiment 1, application of SMC led to increased (P < 0.05) levels of plant-available phosphorus, potas sium and magnesium, soil pH and herbage DM yield. In Experiment 2, both soil type and SMC amendment affected (P < 0.05) all parameters recorded except soil bulk density. Results from both experiments show that SMC has merit as a fertiliser material. However, in view of the high levels of plant available nutrients

(especially P) in Monaghan soils, the practice of

spreading SMC on grassland is questionable.

Physiography, soil and vegetation of a western hill

sheep farm M. Walsh1 and J.F. Collins2

Teagasc, Research Centre, Athenry, Co, Galway and

Department of Crop Science, Horticulture and Forestry, University College Dublin, Belfield, Dublin 4

The relationships between physiography, soil type and

vegetation on an un-improved hill in Co. Mayo were studied over the period 1995 to 1997. Vegetation obser vations were made by a point quadrat using the inter sections of a 100 X 100 m square grid layout. Soil observations (1 m long gauge auger with 1 m exten sions) were also based on this grid. Four distinct phys iographic units each containing discrete elements were identified. Three physiographic elements, a transporta tional mid-slope, a dome peat and a lacustrine peat (mean depths 189 and 215 cm, respectively) were ex amined in more detail. Mean gradients ranged from 18? in the transportational mid-slope to 2? in both the dome and lacustrine peat areas. Organic lithosols (mean

depth 13 cm) occupied 46% of the transportational mid-slope while peat and peaty podzols (mean depths 53 and 38 cm, respectively) occupied almost equal por tions of the remainder. The area of 'no vegetation* decreased over the period by 12% in the transportatio nal mid-slope and by 34% in the dome peat. The

transportational mid-slope contained about twice the amount of grasses and half the amount of sedges as either the dome or the lacustrine peat area. Heathers were 2 to 3 times more prevalent in the dome peat area than in either of the other two physiographic elements.

The main sedge species also showed distinctive pat terns of occurrence by physiographic element. Vegeta tion cover increased and diversified under the present

management system and stocking density (one sheep to 1.25 ha).

New CAP reform and stocking density limits on Irish dairy farms E. O'Leary1*2 and W. Fingleton2 Department of Food Economics, University College, Cork and

2 Teagasc, Rural Economy Research Centre, 19

Sandymount Avenue, Dublin 4

Agenda 2000 Tor a Stronger and Wider Union' pub lished by the European Commission in July 1997, pro

posed making direct payments to farmers, including dairy farmers, 'conditional on the respect of the envi ronmental provisions'. The distributions of stocking densities and possible implications for incomes on Irish

dairy farms of a stocking density limitation were as sessed. National Farm Survey (1996) data were used.

Currently, non-lactating heifers are excluded as live stock units (LU) on farms but the analysis was ex tended to allow for the inclusion of all bovine animals.

The current EU livestock unit calculation is referred to as SD1 and the all inclusive livestock unit calculation as SD2. The average stocking rate for SD1 was 1.39

LU/ha and for SD2 was 1.77 LU/ha on 'all dairy farms' and 1.47 LU/ha and 1.87 LU/ha, respectively, on 'specialised dairy farms'. Applying SD1, 11% of

specialised dairy farms (which account for 12% dairy cows and 12% milk sales in Ireland) have a stocking density greater than 2 LU/ha. When SD2 was applied 39% of farms, 51% dairy cows and 52% of milk sales were affected. The stocking density was higher on farms where herd size was larger. By province, Munster had the highest proportion of intensive specialised dairy farms. Two specialist dairy farms, medium and large,

which exceeded 2 LU/ha when SD2 was applied, were examined in a case study. These farms were considered under two scenarios. In Scenario 1, farms in excess of 2

LU/ha were eligible for payments up to 2 LU/ha. In Scenario 2, farms with more than 2 LU/ha were ineli

gible for premia payments. Scenario 1 would have only minor implications for most Irish dairy farms. If SD2 is

applied, Scenario 2 could have negative consequences for incomes on many intensive dairy farms.

The effect of three contrasting calving patterns on the

grazing management of dairy cows G. Ryan1,2, S. Crosse1 and M. Rath2 1

Teagasc, Moorepark Research Centre, Fermoy, Co. Cork and Faculty of Agriculture, University College Dublin,

Belfield, Dublin 4

Ireland, in contrast with other EU countries, has a

highly seasonal milk supply pattern. The costs associ ated with winter milk production are higher than those for summer milk production. Grazed grass can make a

major contribution to reducing costs in these systems. The objective of this study was to quantify and com

pare grazing management of dairy cows with contrast

ing calving patterns. Seventy-eight cows were assigned to the following treatments on the basis of lactation number, calving date and milk yield: (A) 100%

autumn-calving herd; (B) 50% autumn- and 50%

spring-calving herd; (C) 100% spring-calving herd.

Herbage yield pre-grazing (above 40 mm horizon) and

pre- and post-grazing sward surface heights were mea




sured in all paddocks. The farm cover was visually assessed weekly. The turnout date to pasture in 1996

was 2 April and the cows Were housed full-time on 19 November. The grazing season was divided into four distinct periods for analysis: 8 April to 19 May, 20 May to 28 July, 29 July to 15 September and 16 September to 17 November. A larger area was conserved as a

surplus in treatment A (10.1 ha) than in treatments B and C (7.2 and 7.5 ha). Treatment C had a higher daily herbage allowance of 18.3 kg dry matter (DM)/cow/ day (s.e.1.26) in the final period (16 September to 17 November) than treatment A and B of 11.1 and 14.6 kg DM/cow/day (s.e. 1.52 and 1.39). The post-grazing sward surface height was significantly different for treatment A compared to treatments B and C for the

final three periods (20 May to 28 July, 29 July to 15

September and 16 September to 17 November) (P <

0.01, P < 0.01 and P < 0.001). It was concluded that the

contrasting calving patterns had an effect on the graz ing management of dairy cows throughout the 1996

grazing season.

Effect of lactation stage, season and herbage allowance on the performance of dairy cows J. Maher1, G. Stakelum1 and M. Rath2

Teagasc, Moorepark Research Centre, Fermoy, Co. Cork and Faculty of Agriculture, University College Dublin, Belfield, Dublin 4

Lactation stage and sward quality/structure change with season. The experiments studied the effects of lactation stage, season, and herbage allowance on the

performance of dairy cows. The experiments were car ried out in early summer using spring- and autumn

calving cows, and in late summer using spring-calving cows. Three levels of daily herbage allowance (17, 20 and 23 kg dry matter (DM)/cow) were applied. In

early-summer, the spring-calving cows grazed to a residual herbage yield of 337, 455 and 576 kg DM/ha and a sward height of 4.7, 5.5 and 6.6 cm and the

autumn-calving cows grazed to a residual herbage yield of 401, 498 and 618 kg DM/ha and a sward height of 5.0, 6.0 and 6.9 cm for the low, medium and high allowances, respectively. The spring-calving cows grazed to a residual herbage yield of 430, 565 and 675 kg

DM/ha and a sward height of 5.1, 5.8 and 6.7 cm, for the low, medium and high allowance groups, respec tively, in late summer. There was a response in daily

milk, protein and fat yields in early lactation up to the

highest level of allowance (24.4, 24.9 and 26.2 [s.e.d. =

0.46] kg milk, 0.825, 0.860 and 0.901 [s.e.d. = 0.0185] kg protein, and 1.00, 1.01 and 1.06 [s.e.d. = 0.0222] kg fat for the low, medium and high allowances, respectively)

while in late lactation there was a milk and protein yield response up to the medium level of allowance in the early summer (17.4, 18.5 and 18.8 [s.e.d. = 0.33] kg

milk and 0.651, 0.698 and 0.705 [s.e.d. = 0.0128] kg protein for the low, medium and high allowances, re

spectively). Milk and protein yields and milk protein concentrations were significantly increased up to the

medium level of allowance in late summer (16.9, 18.2 and 18.3 [s.e.d. = 0.61] kg milk, 0.582, 0.643 and 0.656 [s.e.d. = 0.019] kg protein, and 34.5, 35.4 and 36.2 [s.e.d. = 0.39] g/kg protein for the low, medium and

high allowances, respectively). The body weights and condition scores of the cows were not affected by al lowance.

The effect of supplement type on the performance of

dairy cows offered fresh herbage HJ. Sayers and CS. Mayne, Agricultural Research Insti tute of Northern Ireland, Hillsborough, Co. Down BT26 6DR

Responses in animal performance to supplementation at pasture are extremely variable reflecting large varia tions in herbage substitution rate. The objective of this

study was to examine the effect of level of supplemen tation and crude protein (CP) concentration of the

supplement on herbage intake and performance of dairy cows offered fresh herbage indoors. Thirty-six cows were allocated to nine treatment sequences in a par tially balanced changeover design experiment with three, 4-week periods. The nine treatments involved

grass only or grass plus either 3 or 6 kg/day of supple ments containing 100, 180, 260 or 340 g CP/kg fresh

weight. Animals offered herbage as the sole feed con sumed 12.7 kg dry matter (DM)/day and produced 18.2

kg milk/day. At the low level of supplementation (3 kg/day) herbage substitution rate was very low (0.17 kg herbage DM/kg supplement) and unaffected by sup plement protein concentration. Substitution rate in creased to 0.30 kg herbage DM/kg supplement at the

higher level of feeding and increased significantly (P < 0.05) with increased protein concentration. Milk yield

was significantly increased by supplementation, with responses of 0.87 and 0.43 kg milk/kg supplement for the first and second increments, respectively. The re

sponses were primarily related to increased energy in take, with no evidence of a response to increased pro tein supply.

The control of sward structure perennial ryegrass {Lolium perenne L?) I.A. Casey1, AJ. Brereton1, A S. Laidlaw2 and D.A.

McGilloway2 Teagasc, Moorepark Research Centre, Fermoy, Co. Cork

and The Queen's University of Belfast, New forge Lane, Belfast BT9 5PX

Herbage intake by grazing cows is determined by the

position and content of leaf lamina in the canopy. Both are controlled by the way dry matter is apportioned between sheath and lamina in growing leaves. It may be possible to control the balance between sheath and lamina by breeding. The objective of this work was to

determine how the development of individual leaves is affected by altering the light environment within the

pseudostem. The development of a leaf from initiation at the apex to maturity was followed by successive destructive dissections of tillers. Vertical incisions were made in the pseudostem of each tiller to three differ ent depths to vary the radiation environment of the

developing leaf. The three treatments imposed were: no incision (control), moderate and severe incision of the sheath length. Experimental harvests of tillers fol lowed after 3, 6, 9 and 12 days. There were 10 replicate pots for each treatment/harvest. Leaf length and cells of the adaxial epidermis of the harvested developing leaf was measured at each harvest. The length of the leaf was reduced significantly at all harvests while the formation of the sheath was advanced by incision. The

length reduction reflected a reduction in both cell size and cell number and the effects were evident at the




earliest harvest. Treatment leaf lengths at harvest one were 72, 46, 42 (s.e.d. 8.8, P > 0.05) mm. Cell lengths, at harvest 1, were 158, 115, 105 (s.e.d. 13.1, P > 0.05) fim. The results showed that the development of the grass leaf, even at the earliest stages of development, is not

independent of environmental conditions and that the

lamina/sheath ratio is not genetically controlled.

Persistency of Lolium perenne under a range of grass harvesting techniques G. Stakelum1, J. Maher2 and D. McGilloway2

Teagasc, Moorepark Research Centre, Fermoy, Co. Cork and Teagasc, Grange Research Centre, Dunsany, Co.

Meath

Ryegrass swards which are used for silage deteriorate in botanical composition. This experiment studied the effects of silage-cutting factors on ryegrass survival over 5 years. The swards were sown in September 1992. The seeds mixture comprised 90% Lolium perenne, 5% Poa trivialis and 5% Agrostis stolonifera. A split-plot ran domized design with three blocks using ryegrass culti var (either Amigo or Parcour) as the main-plot was used. Sub-treatments were replicated twice and ran domized within the blocks. These comprised 2 N levels for silage

? optimum (150 and 125 kg/ha for first and

second cut, respectively), and optimum +20% (180 and 140 kg/ha for first and second cut, respectively); two

cutting heights of silage ? 4 and 7 cm; three cutting

dates for first-cut silage ?

early, optimum and late (10 May, 24 May, and 7 June) followed by a second cut of

silage 6 weeks later with subsequent monthly cuts to 5 cm. The dominant effect on Lolium content was cut

ting height (P < 0.001), cutting date of first silage (P < 0.001 for autumn '96 and spring and summer of '97), and cutting height by cutting date of first silage (P < 0.001 for both autumn '96 and '97). Lolium content was 0.774 and 0.797 (s.e. 0.0010) in autumn '96, 0.620 and 0.615 (s.e. 0.0090) in spring '97, and 0.428 and 0.485 (s.e. 0.0044) in summer '97, and 0.404 and 0.481 (s.e. 0.0131) in autumn '98 for early and late varieties, re

spectively. The Lolium content was 0.727, 0.860 and 0.629 for the 4 cm cut, and 0.827, 0.862 and 0.806 (s.e. 0.0186) for the 7 cm cut for early, medium and late first

silage, respectively, in autumn '96. The Lolium content was 0.430, 0.398 and 0.373 for the 4 cm cut and 0.393, 0.514 and 0.548 (s.e. 0.0284) for the 7 cm cut for early, medium and late first silage, respectively, in autumn '97. Late cutting in association with 4 cm cutting was the severest treatment for Lolium survival.

Comparative performance of pig terminal sires from seven sources P.B. Lynch1 and P. Allen2

Teagasc, Moorepark Research Centre, Fermoy, Co. Cork and Teagasc, National Food Centre, Dunsinea, Dublin 15

The objective of this study was to evaluate sources of boars available on the Irish market and suitable for use as terminal sires for the production of pigs for slaugh ter at a carcass weight of 65 to 75 kg. Breeders (n = 7; coded A-G) each supplied semen from 20 boars over 2

years (10 deliveries, each from two boars from a termi

nal line). Each boar was mated to five sows which were Fl stock (Landrace X Large White) of parity 2 to 7. At

weaning, one group of 16 males and one group of 16 females were assembled (progeny of two boars from one breeder) and reared to slaughter at an average carcass weight of ca. 72 kg. In the period from weaning to slaughter, there were significant differences in daily growth rate (A 676; B 682; C 664; D 695; E 672; F 679; G 697; s.e. 8 g; P < 0.01), feed conversion efficiency (A 2.18; B 2.19; C 2.23; D 2.13; E 2.25; F 2.19; G 2.15; s.e. 0.03; P < 0.05), and carcass lean meat proportion (A 578; B 582; C 582; D 591; E 575; F 578; G 589; s.e. 3

g/kg; P < 0.01), between progeny of boars from dif ferent breeders. It is concluded that there are signifi cant differences in the economically important traits between sources of terminal sires available to Irish pig producers.

Carcass traits of pig terminal sires from seven sources P.Allen1 andP.B. Lynch2 Teagasc, National Food Centre, Dunsinea, Dublin 15

and Teagasc, Moorepark Research Centre, Fermoy, Co. Cork

Genetic differences in carcass traits could potentially affect the profitability of the pigmeat industry. The

objective of this study was to compare a number of carcass traits of progeny from seven breeding compa nies. Pigs were slaughtered at 65 to 75 kg carcass

weight in groups of four from two boars from the same breeder. Carcasses were split, weighted and linear mea surements were recorded. After overnight chilling the left sides were weighed, jointed and dissected according to the EU approved method. The pH of the muscle

longissimus dorsi (LD) at 45 min and 24 h after slaugh ter, backfat depth, LD area and drip loss were recorded.

Data were collected on between 25 and 38 pigs per breeder (total = 234). The weights of the hind leg, shoulder, back and belly as a proportion of carcass

weight varied little between breeders, differences being significant for the belly only (P < 0.05). There were differences in carcass lean meat percentage, in the

composition of all four main cuts and in all linear measurements and meat quality indicators (P < 0.05). The ranges in mean meat percentage were 52.1 to 55.7 (s.e. 0.54), 71.3 to 75.0 (s.e. 0.64), 62.9 to 66.3 (s.e. 0.81), 54.4 to 59.8 (s.e. 1.11) and 59.6 to 63.6 (s.e. 1.36) for the carcass, hind leg, shoulder, back and belly, respectively. It is concluded that differences exist in carcass traits between these seven sources of terminal sires which could affect the profitability of pigmeat processing.

Effect of feed curve on performance and meat quality of wet-fed finishing pigs P.G. Lawlor and P.B. Lynch, Teagasc, Moorepark Re search Centre, Fermoy, Co. Cork

Feed intake curves for computerised wet-feed systems are often those installed by the manufacturers of the

system and may not be suitable for individual units and

genotypes. The objective of this experiment was to

identify a feed curve to suit the genotype used on most Irish pig farms. Forty-eight groups of 13 pigs averaging 37 kg live weight were blocked on weight and sex and




randomly assigned to three dietary treatments: (1) a low feed curve for 6 weeks followed by a high feed curve to slaughter (LH), (2) a high feed curve for 6

weeks followed by a low feed curve to slaughter (HL), and (3) a high feed curve to slaughter (HH). Using a

Big Dutchman wet-feed system, a 3:1 (water to meal) mix was fed three times daily (24% at 8 am, 42% at 2

pm and 34% at 10 pm). Pigs were weighed after 6 weeks and again at slaughter (ca. 95 kg). Feed troughs were inspected once daily and the allocation was re duced if significant residual feed was found. The calcu lated analysis (g/kg) of the diet fed was 188 crude

protein, 28 oil, 35 crude fibre, 44 ash, 11.2 lysine and 13.6 MJ/kg digestible energy. For the overall trial

period, daily feed intake (DFI)was 1898,1979 and 1996 (s.e. 18) g for LH, HL and HH, respectively (P < 0.01).

Average daily gain (ADG) and feed conversion effi

ciency (FCE) values were not significantly affected by treatment. Kill-out proportion was significantly higher for HL than for either LH or HH (752, 745 and 747 (s.e. 1) g/kg, respectively). Lean meat proportions were

566, 575, and 567 (s.e. 3) g/kg for LH, HL and HH, respectively (P = 0.10). Male pigs had a higher (P< 0.05) DFI, a higher ADG (P < 0.01), a better (P < 0.05) carcass FCE and a lower (P < 0.01) kill-out than female

pigs. It is concluded that reducing feed allocation in the last 4 to 5 weeks before slaughter did not depress overall DFI or ADG, but it increased kill-out propor tion and tended to increase lean meat proportion.

The Danish enzyme-based analysis for the prediction of digestible energy in pig feeds S. Kavanagh1'2, P.B. Lynch1, PJ. Caffrey2 and F. O'Mara2 1 Teagasc, Moorepark Research Centre, Fermoy, Co. Cork


Due to the variation in composition of ingredients, there is a requirement for a rapid and reliable labora

tory technique for the measurement of digestible en

ergy (DE) of pig feeds. The objective of this study was to evaluate the Danish enzyme-based system (EFOS) of measurement of organic matter digestibility for the

prediction of DE of compound feeds for finishing pigs (n = 35). In vivo digestible energy (DEm) measure

ments were obtained from digestibility studies at two

laboratories, namely: Teagasc, Moorepark and Univer

sity College, Dublin (UCD). Digestibility measure ments at Moorepark were made on group-housed ani mals fed ad libitum at ca. 55 and 80 kg live weight (LW) using dietary acid-insoluble ash as a marker. At UCD, animals were housed in metabolism crates, fed a re stricted amount of feed and total faecal collection was

made at ca. 35 to 45 kg LW. In vitro organic matter

digestibility (EDOM) was estimated using a three-step enzyme method. Predicted digestible energy (DEp) was obtained from EDOM by the equation DEp

= -14 + 1.106* EDOM*GEf (GEf

= gross energy of feed). The

correlation between DEp

and DEmwas 0.83 (CV 2.27%) when 35 compound feed samples were analysed. When diets containing rapeseed meal (200 and 400 g/kg) raw, and extruded rapeseed meal were removed from the data set, the correlation improved to 0.90 (CV 1.84%). The in vitro method overestimated digestibility by up to 7% when rapeseed meal was included at high levels. In

conclusion, EFOS can be regarded as a reliable tech

nique for the prediction of digestible energy, apart from diets where a high level of rapeseed meal was included in the formulation.

Pre-slaughter fasting of pigs and it's effect on meat

quality D. Davis1'2, P.B. Lynch1, J.P. Kerry2, DJ. Buckley2 and L.Walsh3 1 Teagasc, Moorepark Research Centre, Fermoy, Co. Cork, 2Department of Food Technology, University College, Cork and 3Galtee Foods, Mitchelstown. Co. Cork

The objective of this study was to determine the effects of feed withdrawal prior to slaughter on carcass meat

quality (pH, colour). The experiment was a 2 X 2 fac torial with two feeding systems (ad libitum dry feeding and three times daily wet feeding) and two fasting periods (long fast ca. 14 h and short fast-fed up to 2 h before slaughter). After slaughter the stomach contents were collected and dried. Carcass pH was measured in the collar region 45 min, 90 min, and 24 h after slaugh ter. At 24 h post-slaughter, the left side of the carcass

was cut at the last rib, assessed using a Minolta Col orimeter and was visually colour scored. There was no

significant effect of feeding system on any variable and there was no significant interaction between feeding system and fasting period. Pigs fasted before slaughter had a higher killing-out proportion (750 v. 722, s.e. 0.5

g/kg, P < 0.01), less wet stomach contents (455 v. 1539, s.e. 133 g, P < 0.01) and less dry stomach contents (65 v. 392, s.e. 41 g, P < 0.01). Pigs fasted for a longer time had darker meat (Hunter a value 6.9 v. 7.7 s.e. 0.3, P < 0.05; Hunter L value 43.8 v. 46.1, s.e. 1.1, P < 0.05; Hunter b value 7.3 v. 8.2, s.e. 0.3, P < 0.05) and a

higher pH in the rib area at 24 h post-mortem (5.74 v. 5.67, s.e. 0.03, P < 0.05). In conclusion, overnight fast

ing before slaughter improves the colour of pig meat.

Effect of mats on behaviour and skin lesions of sows and piglets in the farrowing house L.A. Boyle1-2, F.C. Leonard1, P.B. Lynch1 and P.

Brophy2 Teagasc, Moorepark Research Centre, Fermoy, Co. Cork


The objective of this study was to assess the effect of

providing mats in the farrowing house on behaviour and skin lesions in sows and piglets. Nineteen of 38 sows and their litters housed in farrowing crates with

metal slatted floors were provided with rubber mats. Sow skin was inspected pre-farrowing and at weaning, and piglets were examined at 6 days of age. Lesions were scored (1 to 6) according to severity. Total lesion score per sow and median lesion score per litter were calculated. Sow behaviour was recorded by direct observation at feeding. Usage of the heat pad for lying with and without a mat was assessed over a 2 h obser vation period when piglets were 10 days old. Median skin lesion scores of sows did not differ between treat

ments. Litters from the control treatment had lower skin scores (median, min-max of 8, 2-12 v. 10, 5-21; P < 0.05). Median lesion scores of the front legs tended to be higher for piglets on mats (8, 2-13 v. 4, 2-8;




P - 0.08). Sows on metal flooring lay down faster (15, 2-45 v. 23, 11-54 s; P < 0.05) and slipped more on their front (2.7, 0-8.7 v. 0, 0-1.3 slips/min; P < 0.001) and hind legs (5.3, 0.3-31.7 v. 1.9, 0-33.3 slips/min; P < 0.05). Piglets spent a higher percentage of time

lying on the heat pad (44 v. 25%; P < 0.0001) when it was covered by a mat. It is concluded that mats im

prove sow comfort and can reduce slipping. Mats also

encourage piglets to lie on the heat pad but cause

damage to the skin of the front legs.

Effects of urea inhibition on grain yield and nitrogen uptake in Triticum aestivum L. B. O'Reilly1'2, J.I. Burke1 and EJ. Gallagher2 lTeagasc Oak Park Research Centre, Carlow and de

partment of Crop Science, Horticulture and Forestry, Uni

versity College Dublin, Lyons Research Farm, Newcastle, Co. Dublin

One of the problems associated with the use of urea as a fertiliser is the gaseous loss of urea N as ammonia.

Urea used in the form of an acidic derivative such as urea phosphate or urea sulphate has been shown to

minimise volatilisation by retarding enzymatic hydroly ses of urea. Field trials were carried out in 1997 at two sites; Oak Park, Co. Carlow and Lyons, Newcastle, Co.

Dublin using the cultivar Brigadier, to study the yield effect of various inhibition levels on urea, using a range of phosphoric acid and sulphuric acid to N ratios. Inhibition levels for urea phosphate were 15% N/2% P (low), 15% N/6% P (low-medium), 15% N/10% P

(medium-high) and 15% N/14% P (high), while the

equivalent products for urea sulphate were 23% N/3% S (low), 23% N/6% S (low-medium), 23% N/9% S

(medium-high) and 23% N/12% S (high). Two nitro gen rates were included 100 and 200 kg N/ha plus one untreated. All fertilisers significantly (P < 0.01) in creased grain yield at both sites while increasing inhibi tion levels of urea phosphate led to increased grain yields. Where urea sulphate was used there was a trend of increasing grain yield with increasing levels of inhibi tion but only up to the 23% N/9% S level after which

a drop-off in grain yield was recorded, indicating stronger inhibitory effects of sulphuric acid compared to phosphoric acid. It is concluded that the difference in grain yield and N uptake between inhibition levels of the two fertiliser sources was due to the acid compo nent in these compounds retarding enzymatic hydroly ses of the urea by soil urease resulting in reduced gaseous loss of urea N as ammonia.

The effect of desiccation date and tuber size on the dry matter content of four potato cultivars J. Burke and T. O'Donovan, Teagasc, Oak Park Re search Centre, Carlow

Dry matter (DM) content, together with tuber size are two of the main quality attributes of potatoes. Mini

mum values in both categories are specified when pota toes are processed for fresh chips. The objective of this

study was to quantify the effect of delaying the desicca tion date on DM content in a range of tuber sizes.

Haulm of the cultivars Fianna, Maris Piper, Navan and

Rooster was desiccated 130 and 152 days after planting (DAP) and the tubers graded as follows: 30 to 35, 35 to

40, 40 to 45, 45 to 50, 50 to 55, 55 to 60, 60 to 70, 70 to 80 and 80 to 90 mm. There were significant differences (P < 0.001) in DM content between the four cultivars at all the tuber sizes considered. The DM content of tubers from the sizes 30 to 35, 35 to 40, 40 to 45, 50 to 55 and 70 to 80 mm was not significantly affected by delaying the desiccation date from 130 until 152 DAP. The DM content of tubers in the sizes 45 to 50, 55 to

60, 60 to 70 and 80 to 90 mm increased significantly (P < 0.05) during the same interval. There was a nega tive quadratic relationship between tuber size and DM content for each cultivar. Tuber DM increased with

increasing tuber size and after attaining a maximum, it declined with further increases in size. In Rooster, the

maximum DM values occurred in the 70 to 80 mm sizes at both desiccation dates. For Fianna and Maris Piper,

maximum values were recorded in the 70 to 80 mm and in the 60 to 70 mm sizes at the first and second dates,

respectively. For Navan, the maximum DM values at the corresponding desiccation dates were recorded in the 60 to 70 mm and the 55 to 60 mm sizes, respec tively.

Genetic evaluation of calving ease in Irish Al bulls K. Quinn and D.L. Kelieher, Faculty of Agriculture, University College Dublin, Belfield, Dublin 4

Calving difficulties are a major source of economic loss world-wide. Information on calving ease and related traits for individual bulls is a vital part of an overall bull selection programme. Currently the Department of Agriculture and Food carries out the analysis of

calving ease traits in Ireland using univariate sire model Best Linear Unbiased Prediction (BLUP). Records (n = 500,000), collected since 1979, through the national

calving survey were used. No information was available on either cow or calf identity. This absence precluded analysis using an animal model BLUP and the evalua tion of bulls for the maternal genetic effects on calving difficulty. The data available for analysis included four traits: calving difficulty, calf mortality, calf size and

gestation length. The model used for all traits included effects for Al region, size of cow, sex of calf, sire breed, dam breed, year of calving, season of calving and age of cow. Variance components for sire effects and residual effects were estimated. The heritability for calving dif

ficulty score was 0.10 (s.e. 0.008), for calf mortality 0.01 (s.e. 0.009), for calf size 0.24 (s.e. 0.008) and for gesta tion length 0.27 (s.e. 0.008). Genetic correlations were 0.48 (s.e, 0.059) between calving difficulty score and calf

mortality, 0.50 (s.e. 0.039) between calving difficulty score and calf size, 0.19 (s.e. 0.027) between calving difficulty score and gestation length, 0.44 (s.e. 0.043) between calf mortality and calf size, 0.35 (s.e. 0.046) between calf mortality and gestation length, 0.34 (s.e. 0.025) between calf size and gestation length. These results can be used to obtain the bulls' predicted breed

ing values (BVs) using multi-trait sire model BLUP. This method of analysing data on calving difficulties should prove to be more accurate and reliable than that used heretofore.




The effect of herd concentrate feed level on the genetic evaluation of dairy sires

A.R. Cromie1'2, D.L Kelleher1, FJ Gordon2 and M. Rath1 Faculty of Agriculture, University College Dublin, Belfield,

Dublin 4 and Agricultural Research Institute of Northern Ireland, Hillsborough, Co. Down BT26 6DR

The bulls available to Irish dairy farmers at present have, in general, been proven in countries that feed

high levels of concentrate. Milk production systems in Ireland are grass-based and this raises important ques tions regarding the use of imported bull semen on Irish farms. The aim of this study was to establish (1) how

much of the genetic advantage suggested in an im

ported bull proof can be obtained on Irish farms and (2) whether the ranking of these bulls changes when

they are evaluated on the basis of daughter perfor mance on Irish farms. Data were sourced from 665

dairy farms throughout Ireland that were both milk

recording and had information on the level of herd concentrate input during the period 1992-95. Herds were grouped on the basis of concentrate

input/cow/year into high input (mean concentrate in

put ? 1,514 kg/cow) and low input herds (mean con

centrate input = 505 kg/cow). Milk records consisted

of 305-day lactation yields of milk, fat, and protein. Proofs were obtained for all sires in high and low input herds separately. Proofs of sires that were common to both high and low input herds and that had a reliability of at least 60% in both categories were then regressed on, and correlated with, official US Interbull proofs to address these two questions. Estimated genetic correla tions between proofs of bulls tested in Ireland with their US proofs were above 0.85 for all traits, indicating little evidence of re-ranking of sires between the US and Ireland. However, there was evidence of a large scaling effect. Average regression coefficients between the US and Ireland were 0.52 and 0.32 for high and low

input herds respectively, indicating that US bull proofs over-predict genetic merit for Irish milk production systems

? especially in low concentrate input-herds.

Effect of genetic index and feeding system on the per formance of spring-calving dairy cows in second lacta tion F. Buckley1'2, P. Dillon1, S. Crosse1 and M. Rath2


The objective of this study was to investigate the effect of cow genetic index (CGI) and feeding system on second-lactation Holstein-Friesian dairy cows. A total of 48 high (RBI95 = 134) and 48 medium (RBI95 = 117) genetic index cows were randomly assigned to three

grass-based feeding systems: (A) Moorepark standard

system, (B) high concentrate system, and (C) high grass allowance system. Cows of high genetic index (HGI) produced significantly higher yields of milk (P < 0.001) and milk constituents and had higher feed intake, both

during lactation (P < 0.001) and during the non-lactat

ing period (P < 0.01). They also had lower condition score (P < 0.001) and similar live weight when com

pared to cows of medium genetic index (MGI) at all

stages of lactation. During the dry period the HGI

cows had higher live-weight gain and had a similar live

weight at the start of the third lactation. Feeding sys tem had a significant (P < 0.001) effect on milk produc tion and feed intake but had no effect on live weight or condition score, or on live weight and condition score

changes. There was no significant CGI X feeding sys tem interaction observed for any of the measurements taken. The responses to feeding the higher level of concentrate in feeding system B compared to system A

were 1.12 and 0.92 kg milk per kg of additional concen trate for the HGI and MG1 cows, respectively. The

response to feeding system C was 189 kg/cow when

compared to system A.

Evaluation of dual-purpose dairy cattle in grass-based spring milk production systems P. Dillon, S. Snijders, S. Crosse and F. Buckley, Tea

gasc, Moorepark Research Centre, Fermoy, Co. Cork

The objective of the present study was to measure the

performance of Montebeliarde (MB), Normande (NM), Holstein-Friesian (HF), and Irish Friesian (CL) dairy cattle in a spring milk production system. All four

genetic groups were managed as one herd over 2 years. In 1996, there were 29 animals per genetic group, all in first lactation. In 1997, there were 25 animals per ge netic group, all in second lactation. Genetic group had a significant effect on all milk production parameters measured in both years. The HF group produced the

highest (P < 0.05) milk, fat, protein and lactose yield in both years. The milk production of CL and NM was

similar, while that of the MB was intermediate between CL and HF. The milk, fat, protein and lactose concen trations for NM were higher (P < 0.05) than for CL in both years, with MB and HF intermediate. The mean

yields of fat plus protein over the 2 years were 387, 366, 365 and 448 (s.e. 12.7) kg, for the MB, NM, CL and

HF, respectively. The mean live weights for MB, NM, HF and CL in 1996 were 548, 557, 518, and 518 (s.e. 8.25) kg, and in 1997 were 609, 621, 577 and 590 (s.e. 9.05) kg, respectively. Greatest mobilization of body tissue occurred in HF during lactation as reflected in live weight and body condition score changes and least occurred in MB. The incidence of lameness was higher for NM. Fertility tended to be lower for both HF and

CL than for MB and NM.

Level of protein supplementation of maize silage-based forages for milk production S. Fitzgerald and J J. Murphy, Teagasc, Moorepark Re search Centre, Fermoy, Co. Cork

The objective of this study was to determine the opti mum level of crude protein (CP) in the concentrate for

lactating dairy cows fed forages containing maize silages differing in starch concentration. An all-grass silage (GS) or two mixed forages containing maize silage with either a low (LSM) or a high (HSM) starch concentra tion and grass silage (60:40 dry matter (DM) mix) were offered ad libitum to cows in early lactation (12 cows/forage). Each forage was supplemented with con centrates (6 kg/cow/day) containing 180, 230 or 280 g CP/kg fresh weight according to a change-over design (three periods of 3 to 4 weeks). The respective compo




ail ion* of the GS, LSM and HSM silages were as follow*; DM 192, 214 and 295 g/kg; CP 172, 131 and 123 g/kg DM; starch 0, 0 and 197 g/kg DM; in vitro

DM digestibility 728, 658 and 724 g/kg; pH 3.9,3.7 and 3.7; NH3-N 119, 74 and 51 g/kg total N, and lactic acid

100, 87 and 73 g/kg DM. Replacing GS with LSM or HSM silages increased forage intake (8.8,10.7 and 11.8

kg DM/day, s.e.d. 0.41, P < 0.001). The LSM forage resulted in a similar yield of milk to the GS silage

whereas the HSM forage tended to increase milk yield (23.7, 23.5 and 26.5 kg/day, s.e.d. 1.7). It also increased

milk protein concentration (29.5, 31.5, 32.8 g/kg, s.e.d.

0.90, P < 0.05) and protein yield compared with the GS or LSM forages. Increasing the concentrate CP level had no effect on forage intake but increased milk yield (23.7, 24.4 and 24.7 kg/day, s.e.d. 0.31, P < 0.001) and the yield of fat and protein on all forages without

affecting milk composition. It is concluded that a high level of starch is required in maize silage to improve

milk yield and milk protein concentration compared with grass silage. A crude protein level of about 250

g/kg fresh weight is required in the concentrate sup plement of maize silage-based forages.

Use of plastic film in the cultivation of forage maize D.L. Easson and W. Fearnehough, Agricultural Re search Institute of Northern Ireland, Hillsborough, Co.

Down

In recent years there has been considerable interest in

using plastic films for maize cultivation in Ireland. Whilst it is widely acknowledged that plastic can sig nificantly improve maize yield and quality, further re search is needed to determine appropriate strategies for its use. Research conducted in 1997 examined the interactions between sowing date, use of plastic and

timing of plastic removal. Maize (var. Hudson) was sown at three sowing dates (10 April, 24 April and 27

May) under perforated and total cover plastic (both

photo-degradable). Total cover plastic was divided into five subtreatments, where plastic was either not re

moved, or removed at the 4, 6, 8, 10 leaf stages. Over the three sowing dates, total cover plastic increased

yields by 2.1 t dry matter (DM)/ha (12.9 to 15 t

DM/ha) and DM contents by 4.8% (24.2 to 29%). With total cover plastic, highest DM contents occurred

in the early sown treatments, but highest yield was recorded in the 24 April sown treatments. Delaying plastic removal increased DM content at all sowings, but where plastic was not removed, yields were re

duced, indicating that plastic is best removed at the 8 to 10 leaf stage. Yields under total cover and perfo rated plastic were similar at the two later sowings, but at the early sowing, frost damaged the perforated plas tic treatment, and yields were below that of the control. In conclusion, the increased soil warming and frost

protection afforded by the total cover plastic, allows earlier sowing than with perforated plastic. The desir

ability of this earlier sowing, at least in a warm year like 1997 remains questionable, as there appears to be a trade-off between yield and DM content with earlier

sowing under total cover plastic.

Survey of Fusarium /MUrodochium species on wheat O. McEnery1, E. Bannon1 and E. Walsh2 Department of Environmental Resource Management and 2Department of Crop Science, Horticulture and

Forestry, University College Dublin, Belfield, Dublin 4

The Fusarium /Microdochium species attacking small

grain cereals have become increasingly important economically throughout the world. The objectives of this experiment were to identify the species responsible for causing Fusarium Head Blight in Ireland, and to

compare the difference between spring wheat and win ter wheat with regard to infection levels. A total of 162

wheat samples, each sample comprising 10 intact wheat

plants (including roots, stems and heads) on which

symptoms were visible, were taken from various loca tions around Ireland; Carlow, Cork, Kildare, Kilkenny,

Louth, Meath, Offaly and Westmeath, in July and Au

gust 1997. There were three spring wheat varieties

(Alexandria, Baldus and Chablis) and nine winter wheat varieties (Apollo, Brigadier, Hussar, Reaper, Rialto, Ritmo, Riband, Soissons and Sponsor) covered in the

survey. Four kernels and four segments of rachis from each sample were placed onto Potato Dextrose Agar (PDA). Hyphal tip cultures were made after a period of 3 days, onto both PDA and Selective Nutrient Agar (SNA). After 10 days the cultures were identified. Re sults show that the two main species found causing infection were Fusarium culmorum (30.3%) and Micro

dochium nivale (25.9%). Other species identified were F. avenaceum (7.5%), F. tricinctum (1.9%), F. poae (0.2%) and F. graminearum (0.2%). It was found that

where there were high levels of M. nivale, there were low levels of F. culmorum and vice versa. With regard to differences in infection between spring and winter

wheat, there was a higher incidence of infection in winter wheat (70.5%) than in spring wheat (52.6%).

Growing cereals in a white clover living mulch R.A Hackett1'2, M.L. Reilly1, J.L Burke2 and G. Purvis1

Department of Environmental Resource Management, University College Dublin, Belfield, Dublin 4 and

Teagasc, Oak Park Research Centre, Carlow

Growing cereals in a leguminous living mulch could

potentially reduce the need for synthetic inputs to ce real production while preventing losses of nutrients and increasing soil biological activity. The objective of the present work was to evaluate the use of white clover (Trifolium repens) as a living mulch in winter wheat production under Irish conditions. The study, carried out between 1994 and 1997, comprised two 1 ha fields at Lyons Estate, Newcastle, Co. Dublin, in one of which, the standard farm practice (SFP) field, winter wheat (cv. Hereward) was grown using conventional

husbandry techniques. In the second field, the living mulch (LM) field, winter wheat (cv. Hereward) was direct drilled into a defoliated white clover (cv. Donna) sward and grown with restricted crop inputs. Following

wheat harvest the clover was allowed to re-grow before

being defoliated and the field re-drilled with wheat.

Crop growth, grain yield, clover survival and pest popu




lations were monitored during each year of the study. Above ground wheat dry matter accumulation mea sured in March, May and August and grain yield were

significantly (P < 0.01) lower in the LM field in all three seasons. Clover growth was vigorous during the first two seasons but paraquat application prior to

sowing the cereal crop (to control grass weeds) and

subsequent slug injury resulted in the absence of a clover canopy during the third growing season. Grain

yield was highest in the LM field in the third season (7.12 t/ha, s.e.m. 0.25). Slug populations increased in the LM field during the study. It is concluded that the control of slugs and grass weeds as well as the manipu lation of the cereal/clover balance are required, so that commercial viability of the system can be im

proved.

The long term outlook for Irish cereal prices P.W. Kelly, Teagasc, Rural Economy Research Centre, 19

Sandymount Avenue, Dublin 4

The proposed reform of the Common Agricultural Pol

icy contained in 'Agenda 2000' envisages cuts in the EU intervention price to bring prices closer to 'world market' levels. This study consisted of an analysis of the 'world market' price projections for the next 4

years. The results to date indicate that prices for milling wheat will stay above the EU intervention price from the 1996/97 season until at least 2001/02. The 'world'

price is expected to increase steadily at about 2 or 3%

per year from 1998/99. On this basis EU prices of

milling wheat will increase at about the same rate from their 1998/99 level. The 'world' price of other or 'coarse' grain is projected to stay below the present EU intervention price of 119.19 ECU per tonne over the

whole of the period from 1997/98 to 2001/02. This means that the EU internal price for feed grain, includ

ing feed wheat will be based on this and will be at about the same level as in 1997/98. If the 'Agenda 2000' reforms are introduced, the intervention price will be reduced by 20%. This will bring it below the

projected 'world' price which is about 15% below the current intervention price. The net effect of this will be that Irish feed grain prices will be governed by the intervention price until the year 2000, consequently they will remain at 1997/98 levels until that date. After the year 2000, EU and Irish feed grain prices will fall

by about 15% and then start to rise by about 2% per year in line with projected rises in the prices of coarse

grains. When grain prices are governed by the 'world*

price which is set in dollars, the Irish and EU prices will become sensitive to changes in the exchange rate between the ECU or the Euro and the US$. If the latter strengthens against the European currency this

will lead to higher grain prices. The absence of inter vention purchases once the intervention price is below the world market price will probably cause increased

grain price volatility.

Competitiveness of the Irish pigmeat industry in 1995 and 2000 P.W. Kelly1, A Geary2, B. Lynch2 and S. O'Reilly3 lTeagasc, Rural Economy Research Centre, 19 Sandy

mount Avenue, Dublin 4, 2Teagasc, Moorepark Research Centre, Fermoy, Co. Cork and Department of Food Economics, University College, Cork

Competitiveness is here defined as cost competitive ness. The pig carcass is assumed to be a uniform

commodity and so its ability to retain or increase mar ket share on export markets is dependent on its cost relative to its competitors. In this study the costs (pro duction plus transport) of placing a pig carcass on the German market from Ireland and its main competitors (Denmark, the UK, the Netherlands, Germany and

Hungary) were assessed. The 1995 costs were estimated and these were projected forward to 2000. Hungary was included as it will have easier access to the German

market by 2000 and have access to cheaper grain. In 1995, pigmeat from Denmark had the highest cost on the German market (128 IRp per kg), this was followed

by pigmeat from Germany (126 IRp/kg), the Nether lands (123 IRp/kg), the UK (117 IRp/kg), Ireland (116

IRp/kg) and Hungary (77 IRp/kg). Costs for the year 2000 were estimated by applying appropriate inflators to each of the cost items analysed for the 1995 esti

mates. Feed price projections used a composite index of the price of feed grain (75%) and soya (25%), except for Hungary where only coarse grain price projections

were used. Exchange rate projections for the EU coun tries showed little change in relative currency values but the choice of rates for Hungary was problematic. The relative costs of supplying the German market in 2000 were little changed for all countries except for

Hungary which became more competitive largely as a result of a projected depreciation in the exchange rate.

Effect of cereal cooking on the performance of newly weaned pigs fed a diet with a high or low level of dairy products P.G. Lawlor1-2, P.B. Lynch1 and PJ. Caffrey2 x Teagasc, Moorepark, Research Centre, Fermoy, Co. Cork


The objective of this experiment was to assess the effect of including steam flaked wheat and maize in diets for newly weaned pigs. Ninety-six pigs were weaned at ca. 26 days of age, blocked on sex and

weight and assigned at random to four dietary treat ments as follows: (1) high dairy product diet with un cooked cereal (HDP), (2) high dairy product diet with steam flaked cereal (HDPC), (3) low dairy product diet

with uncooked cereal (LDP), and (4) low dairy product diet with steam flaked cereal (LDPC). Pigs on treat ments HDP and HDPC were fed 6 kg of starter diet (239 g/kg crude protein, 92 g/kg oil, 19 g/kg crude fibre) followed by a link diet (218 g/kg crude protein, 83 g/kg oil, 23 g/kg crude fibre) to 26 days. Pigs on treatments LDP and LDPC were fed 6 kg of starter diet (same formulation as the above link) followed by a link diet (213 g/kg crude protein, 41 g/kg oil, 22 g/kg crude fibre) to 26 days. The level of gelatinised starch as a proportion of total starch was 0.265, 0.840, 0.215 and 0.780 for maize, flaked maize, wheat and flaked

wheat, respectively. Pigs were fed common weaner and finisher diets and individual daily feed intakes were recorded to slaughter. Steaming and flaking the cereals had no effect on pig performance. Feeding a high level of dairy products in the diet increased (P < 0.05) pig weight from 18.5 to 19.5 kg at 26 days. Feed conversion

efficiency (FCE) values from days 0 to 14 on the low




and high dairy product diets were 1.86 and 1.33 (s.e. 0.13, P < 0.01), respectively. FCE values from 0 to 62

days were 1.59, 1.53, 1.58 and 1.64 (s.e. 0.03, P < 0.05) for diets HDP, HDPC, LDP, and LDPC, respectively. It is concluded that including steamed flaked wheat and maize in post-weaning diets has little effect on pig performance.

The effects of reducing dietary digestible energy level on growth performance of individually- and group housed growing pigs R.N. Weatherup1, V.E. Beattie1, KJ. McCracken2 and S.G. Mcllroy3 Agricultural Research Institute of Northern Ireland, Hills

borough, Co. Down, BT26 6DR, 2Department of Agricul ture for Northern Ireland, Newforge Lane, Belfast BT9 5PX and 3John Thompson and Sons Ltd, 35-39 York Road, Belfast BT15 3GW

In a commercial environment growth performance may be significantly below genetic potential since group housed pigs have a lower feed intake than their individ

ually housed counterparts, hence high dietary energy densities are required to maintain high levels of perfor mance. This study was designed to compare the re

sponse of individually- and group-housed pigs to diets

differing in digestible energy (DE) level (15.4, 14.4,13.4 and 12.4 MJ DE/kg) from 8 to 12 weeks of age.

Average daily gain (ADG) of individually-housed pigs was not affected by DE level (mean 856 g/day), but ADG of group-housed pigs was reduced (P < 0.001) at the lower DE levels (642, 635, 594 and 573 g/day, s.e. 10.1). Individually-housed pigs increased (P < 0.001) feed intake with decreasing energy level while group housed pigs had similar intakes at all energy levels. Food conversion ratio deteriorated (P < 0.001) at the lower energy levels in both housing types. In conclu sion, individually-housed pigs responded to reducing

DE levels by increasing feed intake so that daily gain is maintained. Commercially housed pigs did not show the same intake response and daily gain was reduced at the lower DE levels, (i.e. housing system can have a

greater impact on daily gain than dietary energy level). This study highlights the need for a greater under

standing of the factors affecting the voluntary feed intake of growing pigs in groups.

Feed budget for spring milk production M. O'Donovan1'2, P. Dillon1, G. Stakelum1 and M. Rath2 1


The yearly target feed input in the Moorepark spring milk production system (2.75 cows/ha, 320 kg N/ha, mean calving date 1 March) is 3.5 t grazed grass dry matter (DM), 1.3 t silage DM, and 0.45 t concentrate DM. The target outputs from this system are 5823 kg milk at 39 g/kg milk fat and 34 g/kg milk protein. This

production has been achieved on Curtins farm at

Moorepark Research Centre over the period (1990-1993). The objective of this study was to es tablish pasture cover targets over the grazing season.

Grass intakes used were recorded at Moorepark. Graz

ing management used was that recommended by Moorepark. The average of a 6-year (1990-1996) grass growth rate was used. Pasture cover is defined as the

supply of grass in kg DM/ha (> 4 cm) averaged across

paddocks which are being used for grazing. Pasture cover at closing is 325 kg DM/ha. Pre-turnout (early

March) grass cover increased to 600 kg DM/ha. All the farm is grazed initially and from 1 April the herd is stocked at 5.0 cows/ha. Forty-five per cent of the farm is closed for first-cut silage. Pasture cover increases to

between 900 and 1050 kg DM/ha. The grazing area is stocked at 4.5 cows/ha and 35% of the farm is closed for second-cut silage. After harvesting second-cut silage the entire farm is available for grazing and the reduc tion in stocking rate causes a short-term reduction in

pasture cover. The pasture cover subsequently in creases due to increasing rotation lengths. Pasture cover declines below herd demand from mid-August. Con centrate supplementation is introduced initially to counteract the declining grass intake and this is then followed by silage supplementation. Animals are re

moved from the pasture in mid-November. It is con cluded that pasture cover targets are an aid to improv ing cow performance from grazed grass.

The influence of grazing management on herd produc tivity of two spring-calving dairy herds

M. O'Donovan1-2, P. Dillon1, G. Stakelum1 and M. Rath2 1


The objective of this study was to examine the perfor mance from grazed grass of two intensive spring calving herds. The grassland management practices of two farms was monitored for a 13-month period from

November 1995 to December 1996. Both farms had a similar calving pattern and mean calving date was early

March. The cows in both herds were of similar genetic index (RBI95 - 114). The overall stocking rate

(cows/ha) was 2.9 for farm A and 2.7 for farm B. Measurements recorded included pasture cover (kg/dry matter (DM)/ha), grass availability (kg DM/cow/day), grass digestibility, pre- and post-sward surface heights, rotation length, cow condition, level of supplementa tion and herd performance. During the grazing season

(April to October) the average daily milk yield (kg/cow) was 19.8 for farm A and 21.4 for farm B. The protein content (g/kg) of milk produced over this period was 32.8 and 33.9 for A and B, respectively. Total concen trate fed per cow (kg) was 262 on farm A and 177 on farm B; 175 kg silage DM was fed on each farm during this period. The average daily herbage allowance (kg

DM/cow) was 14.5 for farm A and 17.9 for farm B. The average post-grazing sward height was 5.5 cm and 5.8 cm for both farms, respectively. The average cow condition over this period was 2.76 and 3.11 for farms

A and B, respectively. It was evident from the measure ments, that even during periods of normal grass growth when pasture cover was adequate, daily allocation of

grass was insufficient on farm A. Therefore, the results of this study show that grazing management has a large influence on dairy cow performance.




Effect of autumn management on the spring growth of

ryegrass on a wet soil G. Stakelum, F. Kelly, J. O'Loughlin and J. Kiely, Teagasc, Moorepark Research Centre, Fermoy, Co. Cork

This experiment was carried out to study the effects of date and severity of final autumn harvest on the spring growth of a ryegrass sward on a wet soil. There were three levels of autumn defoliation severity (to sward

heights of 8, 6 and 4 cm) and two dates of final autumn defoliation (mid-September and mid-October) in a 3 x 2 factorial arrangement of treatments using a ran domised block (4) design in the 1994/95 and 1995/96 seasons. An extra autumn defoliation date was used in the 1996/97 season which consisted of a mid-Septem

ber followed by a mid-October defoliation. There was no interaction between autumn defoliation date and

severity in any of the years. Autumn defoliation date had no effect on spring yields in 1995. It had a signifi cant effect (P < 0.01) on April and May yield in 1996. There was 2337 and 1823 (LSD = 322.4) kg dry matter

(DM)/ha in April 1996 and 5235 and 4129 (LSD -

765.3) kg DM/ha in May 1996 for the early and late autumn treatments, respectively. Severity of defoliation had a significant effect (P < 0.05) on April yields in both 1995 and 1996. There was 1615, 1327 and 1072 (LSD - 388.4) kg DM/ha in April 1995, and 3789, 3158 and 3242 (LSD = 639.6) kg DM/ha in May 1995 from the 8, 6 and 4 cm treatments, respectively. There was

2317, 2201 and 1722 (LSD = 394.9) kg DM/ha in April 1996 and 4843,4957 and 4246 (LSD = 937.2) kg DM/ha in May 1996, from the 8, 6 and 4 cm treatments, respectively. There was a significant effect of autumn defoliation severity on April (P < 0.05) and May yields (P < 0.01), and a significant effect of defoliation date on April yields (P < 0.01) in 1997. There was 1838,1754 and 1264 (LSD = 461.0) kg DM/ha in April and 4299, 3717 and 3075 (LSD = 627.2) kg DM/ha in May for 8, 6 and 4 cm treatments, respectively. There was 2043, 1545 and 1270 (LSD = 461.0) kg DM/ha and 4032, 3471 and 3589 (LSD = 627.2) kg DM/ha for the early, late and the early/late treatments, respectively. The

organic matter digestibility of the grass was not af fected by treatments in 1995. There was large winter loss of herbage with early and lenient last autumn defoliations. This did not seem to have any detrimental effect on subsequent spring re-growth.

Effect of autumn and spring N level and spring appli cation date on the spring growth of ryegrass on a wet soil F. Kelly, G. Stakelum, J. O'Loughlin and J. Kiely, Teagasc, Moorepark Research Centre, Fermoy, Co. Cork

The experiments were carried out to measure the ef fect and interaction between levels of spring and au tumn N levels and spring application date on the growth of a ryegrass sward in spring. Three levels of autumn N

applied in late October (10, 20 and 30 kg/ha in 1994 and 1995, and 0,15, and 30 kg/ha in 1996), three levels of spring N (40, 50 and 60 kg/ha in 1995 and 1996, and 0, 30 and 60 kg/ha in 1997), and two times of spring N

application (early-February and early-March) were

compared in a 3 X 3 x 2 factorial arrangement of treat ments with a randomised block (three in 1995 and 1996 and four in 1997) design. The only significant effect in

the first 2 years was that of spring N level (P < 0.05) on the early May harvest in 1995. There were yields of 2912, 3158 and 3512 (LSD = 472.5) kg dry matter

(DM)/ha in May 1995 for 40, 50 and 60 kg N, respec tively. There was a significant effect in 1997 of spring N levels on the early May harvest (P < 0.05). The yields

were 3518, 4063, 4194 kg DM/ha (LSD = 516.2) for 0, 30, and 60 kg N/ha, respectively. The interaction between spring and autumn N levels was strong for the

April harvest (P < 0.135), April re-growths (P < 0.146), and the combined April yield and April re-growth (P < 0.061). The combined early April harvest and April re-growth yields were 2480, 3103 and 3530 kg DM/ha at 0 kg/ha spring N, 3423, 3026 and 2950 kg DM/ha at 30 kg/ha spring N, and 3359, 3399 and 3434 kg DM/ha (s.e. = 253.8) for 0, 15 and 30 kg/ha autumn N, respec tively. There was a yield response up to 30 kg/ha of

spring N. The spring N response was much larger at 0 autumn N. The response to autumn N at 0 spring N

was as good as spring N at 0 autumn N. Application date of spring N when first harvesting in April is not

important. Autumn N and spring N appear to be inter

changeable with regard to the spring growth response.

Effect of Lolium variety, cutting height and date and

nitrogen application rate on yield and quality of

herbage G. Stakelum1, J. Maher2 and D. McGilloway2 1

Teagasc, Moorepark Research Centre, Fermoy, Co. Cork and Teagasc, Grange Research Centre, Dunsany, Co.

Meath

This experiment investigated the effect of silage har

vesting factors on the production of ryegrass swards. The swards were sown in September 1992. The seeds mixture comprised 90% Lolium perenne (variety Amigo or Parcour), 5% Poa trivialis and 5% Agrostis stolonifera.

A split-plot randomized design with three blocks using cultivar as the main-plot was used. Sub-treatments were

replicated twice and randomized within the blocks. These comprised two N levels for silage

? optimum

and optimum + 20%; two cutting heights of silage ? 4

and 7 cm; three cutting dates for first-cut silage ?

early, optimum and late, followed by second-silage cut at 6 weeks and monthly cuts to 5 cm. Cutting date had a significant effect (P < 0.001) on all yields in 1996 and 1997. The first-cut silage yields were 3652, 6099, and 8324 (s.e. - 95.9) kg dry matter (DM)/ha in 1996, and 5741, 7396, and 8649 (s.e.= 115.5) kg DM/ha in 1997, for early, medium and late cuts, respectively. The sec ond-cut silage yields were 4924, 4609 and 1652 (s.e.= 52.5) kg DM/ha in 1996 and 3240, 3039 and 3011 (s.e. = 42.1) kg DM/ha in 1997 for the early, medium and late cuts, respectively. The residual effect of first cut silage date on the monthly yields were large but variable between years. The total yields for the monthly cuts were 4529, 4468 and 4581 (s.e. - 58.4) kg DM/ha in 1996, and 5007, 5362 and 4032 (s.e. = 62.2) kg

DM/ha in 1997, for the early, medium and late first

silage cuts. The effect of variety, and its interactions, were small. Cutting-height of 4 cm gave higher silage yields (P < 0.001) compared to 7 cm (10137 and 9369 [s.e. = 93.7] kg DM/ha in 1996, and 10857 and 9861 [s.e. - 97.6] kg DM/ha in 1997). Post-silage harvests

were higher (P < 0.001) for 7 cm compared to 4 cm (4804 and 4248 [s.e. = 47.7] kg DM/ha in 1996, and




5274 and 4236 [s.e. = 50.8] kg DM/ha in 1997). The interaction of cutting height and date of first cut on

first silage yields was different for 1996 and 1997. In all cases, there was more grass harvested from the 4 cm

compared to the 7 cm treatments but differences were small for the late cut in 1996 and the medium cut in 1997.

Influence of pre-calving diet on milk production and

composition post-calving JJ. Murphy, Teagasc, Moorepark Research Centre, Fer

moy, Co. Cork

A previous experiment at Moorepark Research Centre showed no benefit in post-calving performance when a

grass silage diet was supplemented with a low degrad ability protein source pre-calving. The objective of this

experiment was to compare the effects on post-calving performance of pre-calving diets of silage and straw alone or supplemented with fishmeal, or grass silage ad libitum. Fifty-one cows in second or later lactation were blocked into groups of three on the basis of lactation number and expected calving date. Within each group, animals were allocated randomly to one of the fol

lowing three pre-calving treatments: (i) grass silage ad libitum, (ii) grass-silage/barley straw (0.8/0.2 dry mat ter (DM) basis), restricted to a maximum of 9 kg

DM/cow/day, and (iii) grass-silage/barley straw

(0.8/0.2 DM basis), restricted as in (ii) plus 1 kg/day of fishmeal concentrate (0.5 kg fishmeal + 0.5 kg un molassed sugar-beet pulp). Cows on treatment 2 had a lower (P < 0.05) body condition score close to calving (2.78) than cows on treatment 1 (3.21) and gained less (P < 0.05) live weight before calving (0.13 kg/day) than cows on treatment 3 (0.81 kg/day). Treatment 2 cows also had a significantly lower DM intake than treat ment 1 cows (8.5 v. 9.4 kg DM/day). Cow milking performance was measured for 8 weeks after calving. Only milk protein concentration and live-weight change were affected by pre-calving treatment. Milk protein concentration was tower (P < 0.05) on treatment 2 (30.2 g/kg) compared to treatments 1 (31.4 g/kg) and 3 (31.2 g/kg). Live-weight change was positive and dif ferent (P < 0.01) on treatment 2 (0.26 kg/day) com

pared to treatments 1 (-0.27 kg/day) and 3 (-0.18 kg/day). It is concluded that feeding restricted quanti ties of a silage/straw mixture in the dry period resulted in a lower milk protein concentration in early lactation

compared to feeding grass-silage ad libitum. Supple menting this forage mixture with undegradable protein increased milk protein concentration to a level similar to that obtained when grass-silage was the dry period forage.

Effect of concentrate supplements differing in starch, sugar and fibre contents on cow performance

K.P. Cassidy1*2, JJ. Murphy1, F.P. O'Mara2 and M. Rath2

1Teagasc, Moorepark Research Centre, Fermoy, Co. Cork and Faculty of Agriculture, University College Dublin,

Belfield, Dublin 4

It has been suggested that the concentrate energy source fed to dairy cows may influence milk production

and composition. The objective of this experiment was to compare the performance of dairy cows offered four concentrates which were formulated to contain differ ent levels of starch, sugar and fibre and fed with two different silages. Thirty-two multiparous autumn-calv

ing cows were blocked into pairs on the basis of calving date and milk yield and within each pair they were

randomly assigned to one of two treatments each with a different grass-silage. Within each group of 16 cows on each silage they were grouped into squares of four, based on calving date and milk yield. Four concentrates (starch, fibre, starch + fibre, and sugar + starch + fibre)

were fed (8 kg/cow/day) in a balanced latin square within each square. The silages were harvested on 24

May and 7 June, 1996. Both were well preserved (pH 3.8) but differed in dry matter digestibility (DMD) (779 and 739 g/kg dry matter (DM)) and crude protein (CP) concentration (174 and 153 g/kg DM). Concentrates were formulated to contain equal amounts of metabolisable energy (ME), fermentable ME, CP and

undegradable protein but different amounts of starch, sugar and fibre. The ingredients used were barley, un

molassed beet pulp, soya hulls, maize gluten feed, cit rus pulp, soyabean meal, rapeseed meal and cane

molasses. The starch, sugar and fibre concentrations of the concentrates ranged from 72 to 411, 30 to 103, and 67 to 236 g/kg DM, respectively. There was no interac tion between silage DMD and concentrate type. Con centrate type had no significant effect on milk yield (26.3 kg/day), fat yield (1033 g/day), protein yield (838 g/day), fat concentration (39.2 g/kg) or protein con centration (31.9 g/kg). These results indicate that the energy source in the concentrate did not affect cow

performance at a feeding level of 8 kg/cow/day and that there was no interaction between energy source and silage DMD for animal performance.

Composition and processability of milk from spring and autumn-calved herds in mid and late lactation B. O'Brien1, JJ. Murphy1, B. Connolly2 and R. Mehra2 1Teagasc, Moorepark Research Centre, Fermoy, Co. Cork and Teagasc National Dairy Products Research Centre,

Fermoy, Co. Cork

The introduction of early lactation milk in the au

tumn/winter implies that late lactation milk is present in mid to late summer and may have implications for

product quality. This study investigated the processing characteristics of milks produced in the mid/late summer period by autumn and spring-calving cows or a combination of both. Three herds (n = 26) were es tablished with mean calving dates of 28 September, 16

February and a 50:50 combination of both, respectively. The experimental period was from 26 May to 24 Au

gust. Cows were stocked at 2.48/ha. Autumn-calved cows were dried-off 7 weeks prior to calving. Bulk milks were collected from each of the three herds at one consecutive AM and PM milking per week. The milks were analysed for protein fractions, renneting proper ties and free-fatty acids (FFA). Between June and Au

gust, milk from the autumn-calved, spring-carved and combined herds had protein contents of 36.1 (s.e. 0.71) g/kg, 33.8 (s.e. 0.82) g/kg and 35.1 (s.e. 0.89) g/kg, respectively, casein numbers of 76.2 (s.e. 0.96), 77.5 (s.e. 0.87) and 77.8 (s.e. 1.12), curd firmness values of 39.4 (s.e. 5.71) mm, 36.4 (s.e. 4.77) mm and 36.7 (s.e. 4.17)




mm and FFA levels of 0.99 (s.e. 0.28) mmoles/100 g of fat, 0.82 (s.e. 0.21) mmoles/100 g of fat and 0.84 (s.e. 0.14) mmoles/100 g of fat. The spring herd milk had better processing characteristics than the autumn herd milk in terms of lower FFA levels and a higher casein number. Combining mid and late lactation milk re sulted in milk with FFA levels and casein number similar to the spring herd milk (mid lactation). It is concluded that late lactation autumn milk should not

negatively affect the processability of the mixed spring and autumn milk in the mid to late summer period.

Seasonality and milk processability B. O'Brien and J J. Murphy, Teagasc, Moorepark Re search Centre, Fermoy, Co. Cork

More than 85% of manufacturing milk in Ireland is

produced between March and October. Seasonality of

production arises primarily because milk can be pro duced efficiently from grass. Seasonal milk production limits product manufacture during the autumn/winter

months due to the chemical quality of late lactation milk and/or inadequate supplies of milk. Recent re search has suggested methods of overcoming the

processability problems associated with seasonality and

producing year-round products: (i) Improved herd man

agement practices. These include (a) improved cow nutrition (2 kg/cow per day concentrate supplementa tion from mid-September), (b) correct milking manage

ment to reduce somatic cell count (SCC) and free-fatty acid (FFA) levels in milk (8 to 9 1/min claw air admis sion, a maximum milkline height of 1.5 m, float valves in recorder jars and flow-controlled diaphragm milk

pumps) and (c) effective drying-off strategy (average yields should be maintained at greater than 10 kg/cow per day or the herd dried-off). (ii) Segregation of milk

supplies by the processor based on tests such as FFA (> 0.7 mmol/100 g fat), pH (> 6.8), SCC (> 400,000), lactose (< 4.3 g/100 g) or Iactose:protein (< 1.2). (iii)

Blending good quality late lactation milk with early lactation autumn milk. In conclusion, the quality of late lactation milk can be improved by correct herd man

agement practices and by segregation of milk. These measures together with the production of autumn milk should overcome the traditional problems associated

with seasonal milk production and allow the manufac ture of consistent quality short shelf-life products throughout the year.

Effect of animal density at the feed-face on the be haviour of housed cattle (Bos taunts)

MJ. Linnane1,2, AJ. Brereton1 and P.S. Giller2

1Teagasc, Moorepark Research Centre, Fermoy, Co. Cork and department of Zoology, University College, Lee

Mattings, Prospect Row, Cork

Grazing cows display a distinct diurnal feeding pattern. Feeding begins shortly after dawn and ends after sun set. Similar patterns have been observed in housed cattle. The objective of this experiment was to de termine how indoor feeding patterns are affected by competition for space at the feed-face. Sixty-four spring-calving Friesian cows were assigned to four

groups ? two high density groups (24 animals) and two

low density groups (8 animals). The trial was carried out in a conventional design slatted house. Wind expo sure was greater on one side of the shed ? herds were distributed so that one herd of each density was on this side. All groups had access to equal lengths of feed-face

(space/head in high and low density groups, respec tively: 0.4 and 1.1 m/head). A silage/straw/beet-pulp ration of 62.5 kg (fresh weight) was administered per head daily. Refusal weights were taken daily. Animal location and activity were recorded continuously for three 48-h periods in January. No significant differ ences in daily intakes/head due to animal density or side of shed occurred. No significant differences in

length of time spent feeding occurred. Intakes were

analysed using repeated measures analysis of variance.

Chi-square analysis showed that density had no effect on diurnal feeding pattern. Synchronisation of feeding activity with sunrise and sunset occurred. It is con cluded that competition to obtain access to the feed face did not alter intakes at either group density. Per sistence of features of outdoor diurnal activity imply that cattle behaviours are strongly entrained by envi ronmental cues.

Effect of liner design and plant vacuum level on bovine teat-tissue reaction

D.E. Gleeson and E. O'Callaghan, Teagasc, Moorepark Research Centre, Fermoy, Co. Cork

The liner is the only component of the milking ma chine that comes in contact with the cow's teat and can therefore influence pathological teat-tissue changes. In this study, ultrasonography was used to measure

changes in teat-tissue with cows milked with narrow (22.0 mm), medium (28.0 mm) and wide bore (31.6 mm) liners with three system vacuum levels of 40 kPa (low level milk pipeline), 44 kPa (low-level milk pipeline) and 50 kPa (mid-level milk pipeline). The left-sided front and rear teats of cows were scanned before and after milking in two experiments. Experiment 1 was a 6x6 latin square design with six cows milked for a

2-day period with two liner types and three system vacuum levels. Experiment 2 was a 4x 4 latin square design with four cows milked for a 2-day period with two liner types and two system vacuum levels. Measure

ments of teats recorded in millimeters were: teat canal

length (CL), teat diameter (TD), cistern diameter (CD), and teat wall thickness (WT). Increasing system vac uum from 40 kPa to 44 kPa increased TD and WT (P < 0.001) and reduced CD (P < 0.05). Widening liner barrel bore increased WT and reduced CD (P < 0.001). System vacuum levels of 50 kPa and 40 kPa gave similar teat-tissue changes as did wide bore and medium bore liners. It is concluded that widening liner barrel bore and increasing system vacuum level in a low-level

plant can increase the magnitude of teat-tissue reac tion.

Effect of machine milking, teat stimulation and milk

yield on bovine teat-tissue reaction using ultrasonic

analysis D.E. Gleeson and E. O'Callaghan, Teagasc, Moorepark Research Centre, Fermoy, Co. Cork




The milking process may result in short- or long-term effects on bovine teat-tissue. The current study was undertaken to measure changes in teat-tissue after teat stimulation for 30 s, after machine milking, and with two cow milk yield levels of 18 kg and 6 kg/milking using an ultrasound scanner. Eight Friesian cows were milked with simultaneous pulsation in a mid-level plant using wide-bore tapered liners for a 2-day period. The left-sided front and rear teats of cows were scanned before and after milking. Measurements of teats recorded in millimeters were canal length (CL), teat diameter (TD), cistern diameter (CD), and teat wall thickness (WT). Teat length (TL) was measured man

ually using a calibrated syringe. Scan data were stored on video cassette and subsequently measured. Pre

milking teat stimulation increased CD and reduced CL (P < 0.01). Machine milking increased CL, TD, WT and

TL and reduced CD (P < 0.001) relative to pre-milking teat values. Higher cow milk yield increased TL, CL (P < 0.001) and WT (P < 0.01). The ultrasound method

was satisfactory for demonstrating teat-tissue changes. It is concluded that pre-milking teat stimulation, ma chine milking, and increasing cow milk yield result in teat-tissue changes in the short-term.

Current practice in fertiliser usage in tillage crops W.E. Murphy1, N. Culleton1, M. Roche2 and D. Power2

Teagasc, Johnstown Castle Research Centre, Wexford and

2Teagasc, Rural Economy Research Centre, 19 Sandy mount Avenue, Dublin 4

Fertilisers are a significant component of the input costs in tillage farming and it is instructive to ascertain the amounts and types of fertiliser used by tillage farmers. A farm management survey, which incor

porated a fertiliser use component, was conducted in 1995. The sample of farms was drawn up by the Central Statistics Office on the basis of farm size and farming system. The survey was carried out on 1226 farms around the country and 710 of them had a tillage operation on the farm. Mean N, P, K usages for winter wheat were 170, 30 and 82 kg/ha, respectively, and 144, 30 and 81 kg/ha, respectively, for spring wheat

which were broadly in line with Teagasc recommenda tions. The N, P, K usage for spring barley were 104, 27 and 57 kg/ha, respectively. N and P usage were in line

with Teagasc recommendations, while the K usage was a little below normal recommendations. Calcium am

monium nitrate was the dominant source of N used on

cereals, while N, P, K compounds like 10-10-20 and 18-6-12 were the dominant sources of P and K. The

mean usage of N, P and K for potatoes were 121, 101 and 245 kg/ha, respectively. The mean N, P and K

usage for sugar beet was 183, 56 and 203 kg/ha, re

spectively. The N and P usage were somewhat above

Teagasc recommendations. The usage of 150, 73 and 20

kg of N, P and K, respectively, for fodder beet were also above Teagasc recommendations. The mean usage of N, P, K for maize crops were 106, 36 and 54 kg/ha, respectively, with the N usage being in excess of Tea

gasc recommendations.

Weed control in the establishment phase of trees N. Culleton1, A. McLoughlin1 and C. Duffy2 lTeagasc, Johnstown Castle Research Centre, Wexford and

Alegna, Avenue Road, Dundalk, Co. Louth

It has been established that using herbicides to provide a weed-free zone in the immediate environs of trees reduces mortality and increases growth rate in the establishment phase of ash trees. The purpose of this trial was to determine the minimum necessary width of the weed-free zone. Two-year-old bare rooted ash

transplants were pit planted at 2 m x 2 m spacings in the winter of 1992. Each block comprised a single row

of 15 trees of similar size and slope. Within this block the width of the herbicide induced weed-free zone was

gradually increased, with the first tree in each row

receiving no weed control while the fifteenth tree re ceived a weed-free zone of 4 m diameter. There were 12 of these fan-shaped blocks. The herbicide used for each of 4 years was Glyphospate in the early season and Gramoxone in the mid to late season. The initial

mean heights and diameter at 30 cm above ground were 59.3 cm and 6.0 mm, respectively. After 4 years growth, mean heights and widths were 260 cm and 26 mm, respectively. Results indicated no significant effect on tree growth of weed-free zones ranging in diameter from 0.6 m to 4 m. It is concluded that the weed-free zone can be as little as 0.25 m wide on either side 6f the tree.

Performance of semi-refined rape seed oil as a diesel fuel extender

K. McDonnell, S. Ward and P. McNulty, Department of Agricultural and Food Engineering, University College Dublin, Earlsfort Terrace, Dublin 2

Rapeseed oil suitable for use as a diesel fuel extender in agricultural equipment was produced by acidified hot water degumming combined with filtration to five microns. This oil, designated as a Semi Refined Oil (SRO), has a high viscosity compared with diesel. Tests have shown that the maximum viscosity for a fuel, in order to prevent fuel starvation, is ca. 55 mPa at - 12?C. Hence SRO fuel can only be used as a diesel fuel extender, with a maximum inclusion of 25%. A unique method based on accelerated injector fouling combined with 2-dimensional image analysis for assessing injector fouling was developed. This new procedure uses a very rapid engine test cycle (20 min) and was shown to be

equivalent to approximately 2500 h of normal engine operation. A Fouling Index (Fl) was developed which enabled the fouling propensity of various fuel blends to be correlated. The SRO proved to be a suitable diesel fuel extender, at inclusion rates up to 25%, when used

with direct injection engines. Power output was re duced and brake specific fuel consumption was in creased by ca. 0.06% and ca. 0.14%, respectively, for every 1% increase in SRO inclusion rate. Chemical and

viscosity analysis of engine lubrication oil showed that there was no measurable effect on engine oil due to SRO inclusion in diesel fuel. With light duty indirect

injection engines, power was considerably reduced

mainly due to inadequate air-fuel mixing. It was con cluded that SRO can be used as a diesel fuel extender in unmodified direct injection diesel engines. The only

practical difference observed in this study was that the

injectors require more frequent servicing compared with diesel operation. The technology for producing SRO is relatively simple and hence offers the possibil ity of small, locally-based, production units as well as

more larger scale plants.




Yield of marketable cut foliage from a coppiced planta tion of Eucalyptus gunnii over six years

M. Forrest, Department of Crop Science, Horticulture and Forestry, University College Dublin, Belfield, Dublin 4

Cut foliage, a component of floral decorations, is an

expanding crop in Ireland. Packers of prepacked bou

quets require cut foliage with a stem length of 55 cm, occasionally 45 or 65 to 70 cm. Cut foliage for the

floristry market is sold by weight, in 500 g or 1 kg bunches, with a variable stem length. Since 1990, a

coppiced plantation of Eucalyptus gunnii has been cul tivated at University College Dublin. The crop was harvested annually and a record made of stem length, weight and category of foliage, juvenile, adult or dis card. The stems were categorised into lengths of > 50 cm, > 75 cm, > 100 cm, > 150 cm and discard foliage.

A marketable stem was > 20 g and > 50 cm juvenile and adult. The total number of stems recorded was

25,770 of which 6% were > 150 cm, 21% > 100 cm, 23% > 75 cm, 26% > 50 cm and 24% were discards. In the years 1993 to 1997, the proportion of stems > 150 cm long increased from 1.0% to 13.8%. This may be due to less severe pruning in the later years and the

maturity of individual stools. The number of discards increased from 15% in 1994 to 32% in 1997 due to

poor plant growth in part of the site. In this experi ment, coppiced E. gunnii produced stems of varying length. A demand for specific stem length may there fore result in wastage of stems and leaves. Systems of summer pruning or pollarding should be investigated to

provide more uniformity of stem length.

Increasing the range of plants for the nursery stock

industry R.F. Murphy, Teagasc, Kinsealy Research Centre,

Malahide Road, Dublin 17

The main objective of this work is the location, propa gation and evaluation of rare and novel plants which are essential for the continued expansion of the nurs

ery stock industry. One-hundred and sixty cultivars have been successfully collected and propagated from Irish

gardens and plant collections since the project began in 1996. Over 80% are herbaceous or alpine while 20% are woody shrubs or trees, several having arisen as

mutations or seedlings. The main propagation tech

niques used have been mist with a heated bench, graft ing and micropropagation. Mist propagation has proved highly successful for a large range of cuttings of woody and alpine cultivars. Cuttings were taken from Novem ber to March in the case of evergreen subjects and earlier in the year, April to August, for many alpine and some herbaceous plants. For most herbaceous

plants crown or root division was employed during autumn or early spring. Grafting was successful on several species of birch (Betula), thorn (Crataegus), lime (Tilia), crab (Malus) and oak (Quercus). No suc cess was achieved with a cultivar of Betula albo sinensis var. septentrionialis in either 1996 or 1997. Micropropa gation was successfully used for some difficult subjects such as Daphne and Eucalyptus. Difficulty in overwin

tering some subjects such as Azara was overcome by earlier propagation enabling larger plants to be grown

before onset of winter. The plants are being evaluated for commercial potential and are being released to the

industry.

Measurements of vacuum in the cluster using a milk flow simulator

E. O'Callaghan, Teagasc, Moorepark Research Centre, Fermoy, Co. Cork

In field situations, measurements of vacuum conditions in the cluster of a milking unit are of limited use as the low rate in a liner is not known. The flow specification of milking units according to ISO standards (1996) is based on the maximum flowrate of water during a simulated milking to give a fluctuation of 15 kPa at the end of an artificial teat measured over complete pulsa tion cycles. The objective of the present study was to

measure vacuum fluctuations in the cluster using a milk flow simulator with different liner types and pulsa tion characteristics. The flow simulator consisted of four artificial teats with dimensions similar to those

specified in ISO standards (1996). The teat-end vac uum, claw vacuum, and vacuum in the pulsation cham ber were recorded with stainless steel diaphragm type vacuum transducers. The transducer for recording the vacuum in the claw was connected to the top of the claw between the milk entry nozzles. The flowrate of water through the artificial teats was measured by liq uid flow meters. Recordings of vacuum were taken at the apex of one artificial teat, at the top of the claw, and in the pulsation chamber at a flow of 5.2 1/min.

When the liner was open, the mean vacuum at the apex of the artificial teat was 3.1 kPa higher with a wide bore liner than with a narrow bore liner. While the

amplitude of the vacuum fluctuations at the apex of the artificial teat over complete pulsation cycles was 15.2 kPa higher with simultaneous than with alternate pul sation patterns, the mean vacuum when the liner was

open was 3.5 kPa higher with the simultaneous pulsa tion pattern. Measurements of vacuum conditions over

complete pulsation or liner-movement cycles are of limited value in measuring the flow capacity of milking units. The vacuum conditions in commercial milking units can be established with this simulator for a range of flowrates.

Design of a teat seal containing bacteriocin for the prevention of staphylococcal mastitis in dry cows

A.I. Wheelock1*2, WJ. Meaney2, J. Flynn2, C. Hill3 and R.P. Ross1

Teagasc, National Dairy Products Research Centre, Moorepark, Fermoy, Co. Cork, Teagasc, Moorepark Re search Centre, Fermoy, Co. Cork and ^Department of

Microbiology, University College, Cork

To date antibiotics have proven very successful in the

prevention of bovine mastitis. However, due to disad

vantages arising from their use including the disposal of milk with antibiotic residues and the emergence of antibiotic resistant bacteria there is a growing need for safe non-antibiotic treatments particularly in non

lactating cows. The aim of this study was to incorporate lacticin 3147, a bacteriocin produced by Lactococcus lactis DPC3147 which inhibits a broad range of Gram




positive bacteria, into Teat seal for the prevention of staphylococcal mastitis in dry cows. While teat seals alone provide a physical barrier to infection, the incor

poration of lacticin 3147 should provide an effective localised antimicrobial barrier in the teat canal and sinus. Lacticin 3147 (10240 arbitrary units/ml) was found to be bacteriocidal against S. aureus, killing > 99.9% of cells within 2 h. A teat seal product was formulated containing a surfactant which was necessary to achieve sufficient release of lacticin 3147 to inhibit the principle mastitic S. aureus types in-vitro. The local

inflammatory response (irritancy) to the formulation in the teat was found to be acceptable, with no significant sustained increase in somatic cell count. Preliminary animal infection trials on a number of cows showed that quarters treated with teat seal + lacticin 3147 gave

more effective protection (81%) against infection when

compared with untreated control quarters. The combi nation of lacticin 3147 and teat seal should provide a safe and effective alternative to current antibiotic ther

apies.

Fertility rates in Irish dairy herds J. Crilly and KJ. O'Farrell, Teagasc, Moorepark Re search Centre, Fermoy, Co. Cork

In Ireland, surveys in the 1970's have shown calving rates to first service of 60 to 69%. Since then, genetic

merit and milk yield per cow have increased signifi cantly. The objectives of this study were to determine calving rates in Irish dairy herds for the period 1991-1996 and if these had declined over time. Breed

ing records for 58 spring-calving commercial dairy herds maintained on a computerised Dairy Management In formation System (DairyMIS) were analysed. Insemina tions were categorised as either commercial artificial insemination (Al), farmer-operated (DIY) Al or natu ral service (NS). Between 1991 and 1996 there was increased use of DIY Al (P < 0.01) and decreased use of NS (P < 0.05) with no consistent trend in commer cial Al usage. In 1991, roughly one-third of services

were to each of the three service methods, but by 1996 DIY Al accounted for nearly 50% of all services. Calv

ing rates to first service for DIY Al (50.9%) and NS (52.9%) were not significantly different although both

were lower (P < 0.001) than those for commercial AL Overall calving rate for DIY Al (51.4%) was lower (P < 0.001) than that for commercial Al (57.9%) or NS (55.9%). The difference between commercial Al and

NS was also significant (P < 0.05), There was a ten

dency for calving rates to decline over time but this was

only significant in the case of first service to DIY Al (P < 0.01). While there is some evidence of a decline in

fertility levels on DairyMIS farms during the study period, the increased usage of DIY Al, combined with the lower fertility rates associated with this type of service would tend to reduce overall calving rates.

On-harvester forage yield sensing ?

preliminary re sults P.D. Forristal and D. Keppel, Teagasc, Oak Park Re search Centre, Carlow

The development of on-harvester forage yield sensing techniques would benefit forage additive application. It

would also provide improved yield information for

management purposes. The objective of the work de scribed here was to develop and evaluate an on-harves ter forage throughput sensing device. A rectangular force sensing plate was fitted into the grass delivery chute of a metered-chop forage harvester. The plate was connected to an externally-mounted load cell. The

performance of the sensing technique was evaluated in a series of trials over two seasons. An electronic data

logger was used to record integrated force readings from the sensing plate and speed data from sensors fitted to the harvester wheel and chopping cylinder.

Grass was harvested from plots at varying forward

speeds to give a range of throughputs. Individual plot harvests were weighed and throughput was calculated from the plot weight, plot length and forward speed. Sensor performance was evaluated by comparing force

readings with actual throughputs using regression anal

ysis. All six trials showed good relationships between force reading and grass throughput. The relationship

was satisfactorily described by a straight line regres sion, with significance indicated by an F-test probability of P < 0.0001 in all cases. In 1996, the regression re sults for the individual sites were: Field 1 ? R2 0.94 (19 d.f.); Field 2 ?

R2 0.84 (17 d.f.); Field 3 ? R2 0.90 (7 d.f.). In 1997, the results were: Site 1 ? R2 0.96 (26 d.f.); Site 2 ? R2 0.92 (13 d.f.); Site 3 ? R2 0.96 (17 d.f.). It is concluded that the force sensing technique is

capable of indicating forage throughput on a fresh

weight basis.

The effects of spent mushroom compost as a soil amendment on glasshouse tomatoes J. Duggan1,2, MJ. Maher1 and MJ. Hennerty2 1 Teagasc, Kinsealy Research Centre, Malahide Road,

Dublin 17 and 2Department of Crop Science, Horticulture and Forestry, University College Dublin, Belfield, Dublin 4

The Irish mushroom industry produces about 260,000 t of spent mushroom compost (SMC) annually which

must be disposed of in an environmentally friendly manner. The object of this experiment was to assess the suitability of SMC for use as a soil amendment and nutrient source in protected cropping by studying its effect on the yield and quality of tomatoes and also on soil structure and fertility. The SMC was applied at 0, 50, 100 and 200 t/ha and rotavated into the top 20 cm of glasshouse soil into which tomato plants (cv. Triton) were planted. The experimental design was a ran domised block of four treatments with six replications. Soil moisture and bulk density were determined using a sandbox apparatus. The addition of SMC (the following compares the means of the 0 t/ha with the 200 t/ha treatments) increased fruit titrateable acidity from 7.77 to 9.17 mEq per 100 g puree (s.e. 0.34) and fruit K from 2267 to 2467 mg/1 (s.e. 45.4). Fruit yield was not sig nificantly affected being 11.76 and 11.86 kg/m2 (s.e. 0.49) respectively. Soil P measured after the addition of SMC increased from 155 to 236 mg/1 (s.e. 7.27) and K

increasing from 337 to 885 mg/t (s.e. 27.3). Soil NO^N was not significantly affected being 207 and 179 mg/1 (s.e. 18.1) respectively. The soil moisture content mea sured at pFl increased from 46.5 to 53.7% (s.e. 1.4) and bulk density decreased from 1.06 to 0.79 kg/l (s.e. 0.042). It is concluded that the addition of SMC im

proved fruit quality with no yield penalty, improved soil




physical properties and increased soil P and K levels, but was a negligible source of NO J N.

The effect of water quality and rate of lime on the

growth of nursery stock plants in peat MJ. Maher, MJ. Mahon and P.A. Walshe, Teagasc, Kinsealy Research Centre, Malahide Road, Dublin 17

When nursery stock plants are grown in containers, pH may change during the season depending on irrigation water quality. Optimum lime addition may vary with the bicarbonate content. This experiment studied the effect of four rates of lime on the growth of an erica ceous plant, Pieris 'Forest Flame' and Hebe pinguifolia 'Sutherlandii', a non-ericaceous plant, irrigated with hard and soft water. Rooted cuttings were potted, in

May, into 2-litre pots containing peat with dolomitic lime added at 1.0, 2.5, 4.0 and 5.5 kg/m3. The pots

were placed in adjacent flood benches in a glasshouse. Plants on one bench were irrigated with well water

containing 278 mg/1 bicarbonate, while the others re ceived rainwater. On each bench, for each subject, the

experimental design was a randomised block of four treatments with eight replications. Plants were har vested in November, scored for root development and

dry weight measured. Initial pH of the peat was 4.6, 5.2, 5.6 and 5.9 at the four lime rates. Where water was

hard, pH rose to 5.8 and 6.8 at the lowest and highest rates by the end. With rainwater, corresponding levels

were 4.4 and 6.0. Increasing lime from 1.0 to 2.5 kg/m3 reduced Pieris weight from 23.8 to 16.1 g/plant (s.e. 1.8) using soft and from 16.2 to 12.4 (s.e. 1.4) with hard

water. Root score (1 to 5 scale) fell from 4.4 to 2.3 (s.e. 0.3) in soft and from 2.8 to 1.4 (s.e. 0.3) in hard water.

Conversely, Hebe increased from 21.1 to 29.3 g/plant (s.e. 1.5) with a rise to 2.5 kg/m3, using soft water. We conclude that 1.0 kg/m3 of lime is suitable for erica ceous plants and that soft irrigation water is desirable. For non-ericaceous plants a rate of at least 2.5 kg/m3 is needed, especially where water is soft.

The use of digital tensiometers to control the irrigation of containerised nursery stock E. Kehoe1*2, MJ. .Maher1 and A Hunter2

Teagasc, Kinsealy Research Centre, Malahide Road, Dublin 17 and Department of Crop Science, Horticulture and Forestry, University College Dublin, Belfield, Dublin 4

Nursery stock plants grown in small volume peat-filled containers require irrigation. At present most Irish

growers use overhead sprinklers with manual control. This can easily result in sub-optimal irrigation. The aim of this experiment was to study the use of digital tensiometers, placed in the growing medium, to control the scheduling of irrigation under two systems, over head spraylines and ebb and flood irrigation. Eighteen independent growing beds, 5 X 2 m, were used, each

plumbed back to aa individual reservoir. Rooted cut

tings of Viburnum tinus were potted into 2-litre pots, placed on the beds in early June and grown until the

end of October. A digital tensiometer set to trigger an

irrigation cycle at tensions of 50, 100 or 200 hPa was

placed in a pot in each of the beds. The three tensions and the two irrigation systems were combined in a 3x2 factorial design with three replications. The ten siometers were connected, via an input/output (IO) unit, to a PC which controlled the irrigation systems. Time Domain Reflectometry sensors were used to monitor the moisture content of the growing medium. Plots irrigated at tensions of 50, 100 and 200 hPa were watered 30, 19 and 10 times respectively (s.e. 1.3) dur

ing the growing period. There was no difference between the irrigation systems. Plant weight and leaf area was not affected by treatment, dry weights at the end of October being 10.2, 11.9 and 11.0 g/plant (s.e. 0.62) and leaf areas, 466, 537 and 483 cmyplant (s.e. 22.1). It was concluded that tensiometers can be satis

factorily used for irrigation control of containerised

nursery stock plants. At tensions greater than 50 hPa, the number of irrigations is markedly reduced, however in a wetter than average season this did not effect plant development.

Sheep production in Ireland and New Zealand L. Connolly, Teagasc, Research Centre, Athenry, Co. Gal way

The future of the Irish sheep sector depends on its technical and financial efficiency relative to our main

competitors. The objective of this study was to compare sheep production in New Zealand and Ireland in terms of structure, marketing, technical and financial perfor mance. Data on structure and prices were obtained from official sources for the 1996 year, whilst technical and financial performance were based on 1995 farm

survey data of lowland flocks. New Zealand prices, costs and margins were converted to Irish currency using average annual exchange rates. Sheep and wool

output in New Zealand was IR?794 million compared to IR?198 million in Ireland. There were 17,700 sheep farmers in New Zealand (average flock size 1,977 ewes) compared to 47,000 in Ireland (average flock size 106 ewes). In the period 1995 to 1997 lamb prices were

consistently lower in New Zealand where the average annual prices was IR?0.72 compared to IR?2.13 per kg carcass in Ireland. The stocking rate was 10.4 ewes/ha for New Zealand and 9.1 for Ireland. Weaning rates

were 1.20 and 1.27 Iambs per ewe joined to the ram for N. Zealand and Ireland, respectively. Carcass weight (kg) was heavier in Ireland (18.5) than in New Zealand (15.5) in 1996, but the trend is towards heavier car casses in New Zealand. Output per ha was IR?273 in New Zealand compared to IR?621 in Ireland. Direct costs of production were only IR?70/ha in New Zealand compared to IR?206 in Ireland. Overhead costs of production were also IR?67/ha lower in New Zealand but net margin per ha in Ireland was IR?205

compared to IR?60 in New Zealand due to the differ ence in output in the two countries. In conclusion, New Zealand sheep producers are technically more efficient and have lower production costs than Irish producers but obtain lower profit margins due to lower product prices and the absence of direct payment.



Documents

Abstracts of Papers Presented at the 4th Annual Agricultural Research Forum, 19 and 20 March, 1998