6
Use of pymarc as a nitrogen source for grazing dairy calves J.M. Waweru a , S.A. Abdulrazak a, T , T.A. Onyango b , T. Fujihara c a Department of Animal Science, Egerton University, PO Box 536, Njoro, Kenya b National Animal Husbandry Research Centre, PO Box 25, Naivasha, Kenya c Laboratory of Animal Science, Shimane University, Matsue-shi 690, Japan Received 21 October 2003; received in revised form 21 January 2005; accepted 3 February 2005 Abstract A study was conducted to determine optimal levels of pymarc inclusion as a protein supplement to Chloris gayana during the dry season. Forty Friesian dairy calves of 65 F 7 kg weight, 20 each of males and females, were randomly allocated to a 10- diet treatment in a completely randomized design in a factorial arrangement. The treatment diets were: control, 7.5, 15, 22.5, and 30 g DM/kg W 0.75 pymarc, with (PBM) or without molasses (PB). Live weight gains, intake, diet digestibility, rumen pH, and rumen ammonia nitrogen were assessed in the 60-day experiment. Herbage intake did not differ ( P N 0.05) among the treatments. Total intake was in the range of 2072–2636 g/day, diet digestibility 565–582 g/kg, and ADG 157–330 g/day, and differed ( P b 0.05) with supplementation. The results showed that rumen pH did not differ significantly ( P N 0.05) between the treatments, ranging between 6.97 and 7.17. Rumen NH 3 –N control groups PB and PBM had 109.9 and 106.5 mg/l, respectively, while those supplemented increased linearly ( P b 0.05) to 166.5 and 177.14 mg/l, respectively, at the highest level of supplementation. The nutritional profile and potential degradation level of pymarc as well as the performance of calves indicate the latent value as a supplement in providing nitrogen to poor-quality basal diets in the dry season. D 2005 Published by Elsevier B.V. Keywords: Pymarc; Molasses; Calves; Intake; Average daily gain 1. Introduction The demand for animal products in human diet is steadily and substantially increasing with the increasing population, which is expected to be higher than the production by the year 2010. This demands an increase of livestock production (out- put) and productivity (output per unit input) (Delgado et al., 2001). However, lack of adequate quantity and quality of feed is a major constraint especially in the dry season (Walshe et al., 1991). This is evidenced by high calf mortality (15–20%), morbidity, and low body weight gain of calves at farm levels (Gitau et al., 1994). This scenario has led to diminishing replacement stocks, while delay- ing age at first service, or more likely the servicing 0301-6226/$ - see front matter D 2005 Published by Elsevier B.V. doi:10.1016/j.livprodsci.2005.02.004 T Corresponding author. Division of Research and Extension, Egerton University, PO Box 536, Njoro, Kenya. Tel.: +254 51 62550; fax: +254 51 62442. E-mail address: [email protected] (S.A. Abdulrazak). Livestock Production Science 96 (2005) 233 – 238 www.elsevier.com/locate/livprodsci

Use of pymarc as a nitrogen source for grazing dairy calves

Embed Size (px)

Citation preview

Page 1: Use of pymarc as a nitrogen source for grazing dairy calves

www.elsevier.com/locate/livprodsci

Livestock Production Scien

Use of pymarc as a nitrogen source for grazing dairy calves

J.M. Wawerua, S.A. Abdulrazaka,T, T.A. Onyangob, T. Fujiharac

aDepartment of Animal Science, Egerton University, PO Box 536, Njoro, KenyabNational Animal Husbandry Research Centre, PO Box 25, Naivasha, KenyacLaboratory of Animal Science, Shimane University, Matsue-shi 690, Japan

Received 21 October 2003; received in revised form 21 January 2005; accepted 3 February 2005

Abstract

A study was conducted to determine optimal levels of pymarc inclusion as a protein supplement to Chloris gayana during

the dry season. Forty Friesian dairy calves of 65F7 kg weight, 20 each of males and females, were randomly allocated to a 10-

diet treatment in a completely randomized design in a factorial arrangement. The treatment diets were: control, 7.5, 15, 22.5,

and 30 g DM/kg W0.75 pymarc, with (PBM) or without molasses (PB). Live weight gains, intake, diet digestibility, rumen pH,

and rumen ammonia nitrogen were assessed in the 60-day experiment. Herbage intake did not differ (P N0.05) among the

treatments. Total intake was in the range of 2072–2636 g/day, diet digestibility 565–582 g/kg, and ADG 157–330 g/day, and

differed (P b0.05) with supplementation. The results showed that rumen pH did not differ significantly (P N0.05) between the

treatments, ranging between 6.97 and 7.17. Rumen NH3–N control groups PB and PBM had 109.9 and 106.5 mg/l, respectively,

while those supplemented increased linearly (P b0.05) to 166.5 and 177.14 mg/l, respectively, at the highest level of

supplementation. The nutritional profile and potential degradation level of pymarc as well as the performance of calves indicate

the latent value as a supplement in providing nitrogen to poor-quality basal diets in the dry season.

D 2005 Published by Elsevier B.V.

Keywords: Pymarc; Molasses; Calves; Intake; Average daily gain

1. Introduction

The demand for animal products in human diet is

steadily and substantially increasing with the

increasing population, which is expected to be

0301-6226/$ - see front matter D 2005 Published by Elsevier B.V.

doi:10.1016/j.livprodsci.2005.02.004

T Corresponding author. Division of Research and Extension,

Egerton University, PO Box 536, Njoro, Kenya. Tel.: +254 51

62550; fax: +254 51 62442.

E-mail address: [email protected] (S.A. Abdulrazak).

higher than the production by the year 2010. This

demands an increase of livestock production (out-

put) and productivity (output per unit input)

(Delgado et al., 2001). However, lack of adequate

quantity and quality of feed is a major constraint

especially in the dry season (Walshe et al., 1991).

This is evidenced by high calf mortality (15–20%),

morbidity, and low body weight gain of calves at

farm levels (Gitau et al., 1994). This scenario has

led to diminishing replacement stocks, while delay-

ing age at first service, or more likely the servicing

ce 96 (2005) 233–238

Page 2: Use of pymarc as a nitrogen source for grazing dairy calves

J.M. Waweru et al. / Livestock Production Science 96 (2005) 233–238234

of heifers with a poor weight for age, which

inevitably results in poor heifer conception and

lactation. By-products like pymarc may have poten-

tial to mitigate feed shortage during the dry season.

Pyrethrum marc (pymarc) produced in large quanti-

ties in Kenya is the waste product after dried

pyrethrum flowers have been ground and pyrethrins

extracted with petro ether. The material is further

treated by steam to remove any residual petro ether

and to destroy the very small percentage of

pyrethrins remaining after extraction (Ayre-Smith,

1956). Extensive work has been done on the

nutritional value of by-products such as fishmeal,

oilseeds, molasses, and bran; however, limited work

has been reported on pymarc as a supplement for

growing calves. The objective of this experiment

was to determine the potential nutritive value of

pymarc based on chemical composition, fibre,

minerals, phenolic concentration in vitro, in sacco

degradation, and the effects of incremental levels of

pymarc as a protein supplement to Rhodes grass

pasture by Friesian dairy calves.

2. Materials and methods

2.1. Chemical analysis

Dry matter (DM), ash, and nitrogen (N) content

were measured according to AOAC (1990). Neutral

detergent fibre (NDF), acid detergent fibre (ADF), and

acid detergent lignin (ADL) were determined accord-

ing to Van Soest et al. (1991). Mineral content was

determined by atomic absorption spectrophotometry

(Varma, 1991). Phenolic compounds were determined

as described by Julkunen-Titto (1985). Chromium

oxide content in faeces was determined by atomic

absorption spectroscopy according to the method of

Williams et al. (1962).

2.2. In sacco and in vitro digestibility

The rate and extent of degradation of the pymarc

were determined in fistulated Friesian steers using

the nylon bag technique (arskov et al., 1980) as

described by Abdulrazak and Fujihara (1999). The

DM disappearance values were fitted to the expo-

nential equation of arskov and McDonald (1979),

where the degradation curve is described as: within a

lag time T, y =A, which is the initial washing loss;

beyond the time T, y =a + b (1�e�ct) where:

y =percent degraded time t, a =an intercept repre-

senting the portion of dry matter at initiation of

incubation (time 0), b =the portion of dry matter

potentially degraded in the rumen, c =a rate constant

of degradation of fraction b , and t = time of

incubation.

Samples were incubated in vitro in rumen fluid–

buffer mixture in calibrated glass syringes following

the procedure of Menke and Steingass (1988).

Rumen liquor was obtained from two steers main-

tained on a similar diet to those of degradability

studies. Air-dried and ground (1.0 mm) pymarc

samples of about 200F5 mg were weighed. The

syringe pistons were lubricated with VaselineRpetroleum jelly to ease movement and to prevent

escape of gas. Thirty (30) milliliters of the mixed

rumen fluid plus buffer was used to inoculate the

200F5 mg samples placed in the 100-ml gas-tight

graduated glass syringes. The syringes were incu-

bated in a water bath maintained at 39F0.1 8C, andgently shaken every hour during the first 8 h of

incubation. Readings were recorded during 0, 3, 6,

12, 24, 48, 72, and 96 h after incubation. Organic

matter digestibility and metabolizable energy values

of feeds were calculated using 48-h gas production

values as described by Abdulrazak and Fujihara

(1999).

2.3. Feeds and supplements

The calves were grazed on Chloris gayana pasture,

supplemented with 100 g of bran and increasing level

of pymarc at control, 7.5, 15, 22.5, and 30 g DM/kg

W0.75 with or without molasses (PBM and PB),

respectively. The calves were offered a complete

mineral lick (Afya BoraR stock Lick) and clean water

at all times.

2.4. Measurement of intake and digestibility

Each day, the calves were dosed with two paper

capsules containing 2.5 g of powdered chromium (III)

oxide during each supplementation. After 6 days of

adaptation, two faecal grab samples were taken daily

during supplementation for a period of 5 days. The

Page 3: Use of pymarc as a nitrogen source for grazing dairy calves

Table 2

In vitro gas production (ml/200 mg DM) and DM degradation

characteristic of pymarc and Rhodes grass

Gas production 24 h 48 h a +b (ml) OMD48 (h)

Pymarc 49.1 60.4 70.6 74.3

Rhodes grass 27.7 41.6 53.6 57.0

DM degradability 24 h 48 h A B A + B

Pymarc 24.9 36.7 10.1 51.6 61.7

Rhodes grass 23.5 31.5 3.5 46.4 49.9

a and b are constants in the equation (arskov and McDonald

1979). OMD48 (h)= in vitro organic matter digestibility calculated

from the equation: OMD (%)=18.53+0.9239 gas production (a

48 h)+0.054 CP (Menke and Steingass, 1988). A=washing loss

B =portion degraded with time (arskov and McDonald, 1979).

J.M. Waweru et al. / Livestock Production Science 96 (2005) 233–238 235

daily samples were bulked and dried in an oven at 65

8C and analysed for DM, OM, and chromium oxide

content.

Intake was estimated from the ratio between the

faecal output collected for the portion attributable to

the concentrate and indigestibility of the herbage

using the equation of Malossini et al. (1996): HI (kg

OM day�1 ) = (D �R /F �1 c � ( 1 �OMDc ) ) /

1�OMDh), where HI is herbage intake; D is the

quantity of Cr2O3 administered; R is the recovery of

the marker in faeces; F is its concentration in faeces

(g/kg OM); and 1c is the quantity of concentrate fed

(kg OM). The term 1c� (1�OMDc) represents

faecal output from concentrate; OMDh was deter-

mined in vivo where three calves were confined for

10 days. The total amount of faeces excreted each

day was recorded and a sample of 10% was taken

for DM and OM analysis, respectively. The digest-

ibility of the supplemented animals was calculated

by fitting the values to the formulae OMD=1� (D�R/F)/HI (kg OM day�1) (Malossini et al., 1996).

2.5. Statistical analysis

The data on dry matter intake (DMI), average

daily gain (ADG), and diet digestibility were

subjected to analysis of covariance using the general

linear model of SAS computer package (SAS, 1987).

Initial liveweight was used as a covariant in the

analysis of DMI and liveweight changes. The model

included the effect of molasses. An F test at 5%

probability level was used to test for significance and

Table 1

Chemical composition, phenolic concentration, and mineral

concentration in pymarc

Composition Phenolics Minerals

(% DM) (% DM)Macrominerals

(% DM)

Microminerals

(ppm)

CP 14.00 TEPH 5.19 Ca 0.37 Zn 36.95

OM 92.69 TET 2.57 Mg 0.14 Cu 45.00

EE 3.12 CT 0.03 P 0.08 Fe 671.00

NDF 36.95 S 0.09 Mn 33.60

ADF 33.91 Al 0.06 Co 3.89

ADL 10.50

CP=crude protein; NDF=neutral detergent fibre; ADF=acid

detergent fibre; ADL=acid detergent lignin; OM=organic matter;

EE=ether extract; TEPH=total extractable phenolics; TET=total

extractable tannins; CT=condensed tannins.

0

20

40

60

80

100

0 3 6 12 24 48 72 96

Incubation (Hrs)

Deg

rada

bilit

y

Pymarc

Rhodes grass

Fig. 1. In sacco DM degradation of pymarc and Rhodes grass hay

(basal diet) used in the study.

,

t

;

significantly different means separated using orthog-

onal contrasts.

3. Results

The results of chemical composition, phenolic

concentration, and mineral concentration of pymarc

supplement and Rhodes grass are presented in Table

1. The results of the in vitro gas production and dry

matter degradability of pymarc supplement and

Rhodes grass roughage are shown in Table 2, while

results of the in sacco dry matter degradability of

pymarc supplement and Rhodes grass roughage are

demonstrated in Fig. 1. Table 3 shows the mean DMI,

OMI, ADG, diet digestibility, rumen pH, and rumen

NH3–N obtained in the experiment. Low acceptability

Page 4: Use of pymarc as a nitrogen source for grazing dairy calves

Table 3

Intake, ADG, digestibility, pH, and rumen NH3–N in calves grazed Rhodes grass pasture supplemented with pymarc

Level of supplement (g DM/kg W 0.75)

Molasses 0 7.5 15 22.5 30 S.E.M.

Diet intake

DMI (kg/day) B � 2.00a 2.12 2.13a 2.05a 1.96a 0.014

+ 2.02a 2.15a 2.03a 2.06 1.89a

T � 2.07c 2.30bc 2.50 ab 2.60a 2.60a 0.014

+ 2.11c 2.34bc 2.41ab 2.64a 2.63a

OMI (kg/day) B � 1.70a 1.83a 1.91a 1.93a 1.86a 0.012

+ 1.72a 1.87a 1.93a 1.91a 1.90a

T � 1.79c 2.01b 2.29a 2.48a 2.34a 0.012

+ 1.79c 2.19b 2.36a 2.54a 2.62a

ADG (g/day) � 157a 228b 276c 293c 296c 4.770

+ 169a 241b 289c 308cd 330d 3.970

Digestibility

DMD (g/kg DM) � 565c 570b 570b 570b 582a 0.050

+ 565c 570b 570b 571b 573b

OMD (g/kg DM) � 571.26e 581.29d 597c 611b 624a 0.070

+ 570.26e 580.85d 596c 612b 625a

pH � 7.06a 7.04a 7.07a 6.97a 7.17a 0.03

+ 7.11a 7.14a 7.08a 6.99a 6.99a

Rumen NH3–N (mg/l) � 109.9a 138.2b 155.9bc 170.1c 166.5c 8.530

+ 106.3a 148.8b 155.9bc 166.5c 177.1c

a,b,c Means within a row with different superscript are significantly different ( P b0.05); B=basal diet; T= total diet (B+supplement).

J.M. Waweru et al. / Livestock Production Science 96 (2005) 233–238236

of pymarc was observed during the first 3 weeks of

the experiment; however, during the subsequent

weeks, all pymarc offered in all treatments was

consumed except at the level of 30 g DM/kg W 0.75

without molasses. Supplementation did not have a

significant effect on basal diet (B) intake. TDMI,

TOMI, and ADG were different (P b0.05) (Table 3).

The values for apparent digestibility indicated that the

control groups had the lowest DM and OM digesti-

bility. The pH value ranged between 6.97 and 7.17,

while rumen NH3–N ranged between 106.5 and 177.1

mg/l and was different.

4. Discussion

The results of chemical composition (Table 1)

were within the reported ranges of 11.8–14.38%

crude protein in other works on pymarc (Irungu et

al., 1981; Kitilit et al., 1996; Muiruri et al., 2001).

Mineral concentration compares and also contrasts

with what has been reported in other works with

pymarc (Griffin, 1974; Thomas, 1975). Calcium is

closely related to phosphorus metabolism and a

dietary Ca:P ratio of 1:1 to 2:1 is assumed to be

ideal for growth and bone formation (Underwood,

1981). Griffin (1974) reported a ratio of 1.88:1, while

ratios of 4.6:1 were obtained in this work. Factors

such as soils, climate, and season contribute to

variation in the concentration of minerals (Spears,

1994). This ratio, however, does not affect the

performance of calves; Ca:P ratios in the range of

1:1 to 7:1 have been shown to have no effect on

calves’ performance (Underwood, 1981). Iron

requirements of ruminants are not well established

(Underwood, 1981); however, NRC (1989) suggested

30–100 ppm. Although a level of 671 ppm was

obtained, the level is below the maximum tolerable

level of 1000 ppm for cattle (NRC, 1989). Never-

theless, iron is rarely of practical concern in grazing

animals, except in circumstances involving blood loss

or disturbance of iron metabolism as a consequence

of parasitic infestation or disease (McDowell, 1985).

A copper concentration of 45 ppm was obtained;

although higher than that reported by Griffin (1974),

this level is within the minimum requirement and the

maximum tolerable limit of 10–100 ppm, respec-

tively, reported in cattle (NRC, 1989). Other minerals

Page 5: Use of pymarc as a nitrogen source for grazing dairy calves

J.M. Waweru et al. / Livestock Production Science 96 (2005) 233–238 237

compare favourably with the reported work (Griffin,

1974; Thomas, 1975).

Supplementation of C. gayana pasture with

pymarc diets with (PBM) or without molasses

(PB), respectively, was different although not sig-

nificant, ranging from 1699 to 1899 g/day. The lack

of increase in intake of the basal diet is suggested to

be due to adequate content of CP in the basal diet of

C. gayana (72 g/kg DM), which meant that intake

was not limited. Therefore, since the rumen microbe

requirements for nitrogen had been met, additional

high-quality pymarc had no further stimulating effect

on the intake of the basal diet. Gulbransen (1974)

reported that supplements substitute part of the basal

diet; however, he showed further that the degree of

substitution was greater for poor-quality forage than

high-quality forage. The increases in total DMI

results are consistent with other works (Irungu et

al., 1981; Kitilit et al., 1996). An increase in intake

could probably be due to the small particle size of

pymarc, which increases the outflow rate and

reduces the rumen retention time, hence boosting

intake. Minson (1982) reported increased intake by

14–77% following provision of supplementary pro-

tein. An establishment of a suitable rumen environ-

ment that aids digestion could also explain the

increased intake.

Improvement of ADG and diet digestibility prob-

ably occurred as a result of the higher nutritive value

of pymarc and the reduction on the fibre and

improved rumen environment. Improved liveweight

gains have also been reported on roughage diets

supplemented with pymarc (Irungu et al., 1981; Kitilit

et al., 1996). The better response of PBM to PB could

be attributed to a more suitable rumen environment as

a result of supplying readily available source of

energy (molasses) to micro-flora, which in turn leads

to a high microbial activity leading to higher NH3–N,

increased TDMI and TOMI, and improved diet

digestibility. This is a phenomenon of synchronization

of energy and protein, which results in a better supply

of energy and protein to microbes and hence a more

efficient microbial protein synthesis (Sinclair et al.,

1995). It could also be explained by the elevation of

feed intake and improved diet digestibility.

Total gas production varied, with pymarc showing

higher gas production than Rhodes grass, which was

also reflected in higher OMD (48 h) of 74.34% and

56.97%, respectively. The OMD shows that pymarc

has the potential to supply metabolisable energy more

efficiently than Rhodes grass, adding to its value as a

nitrogen supplement. Changes in digestibility (in vitro

dry matter digestibility—IVDMD) are associated with

increasing NDF (fibre) content. The higher rate of

potential degradation (Table 2) observed may be

related to the higher content of NDF in Rhodes grass

(72%) relative to 37% in pymarc. Similar trends in

degradation have been reported (Kitilit et al., 1996)

using pymarc and sorghum silage with NDF of 53.3%

and 77.8%, respectively. The nutritional profile and

potential degradation level of pymarc is an indicator

of the latent value as a supplement in providing

nitrogen to poor-quality basal diets.

The rumen pH was above 6.2, a value suggested to

be a critical level in initiating cellulosis (Mould and

arskov, 1984) for PBM and PB diets. Rumen NH3–N

ranged from 106.5 to 177.14 mg/l. This value is well

above the stipulated threshold of 45–60 mg/l (Kanja-

napruthipong and Leng, 1998). It is possible that the

supplement diet created a more suitable rumen

environment in supplying a ready source of energy

for microflora, which in turn led to higher microbial

activity and NH3–N turnover. It was concluded that

pymarc is a good nitrogen source for dry season

feeding.

Acknowledgement

Financial assistance for this research from Egerton-

KARI collaboration is gratefully acknowledged.

References

Abdulrazak, S.A., Fujihara, T., 1999. Animal Nutrition. A

Laboratory Manual. Kashiwagi Printing Company, Matsue-shi,

Japan, p. 44.

Association of Official Analytical Chemists (AOAC), 1990. Official

Methods of Analysis. Washington, DC.

Ayre-Smith, R.A., 1956. Pyrethrum waste as a stock feed. Field and

Farm, 1956.

Delgado, C.L., Rosengrant, M.W., Meyer, S., 2001. Livestock 2020:

the revolution continues. Paper Presented to the International

Agricultural Trade Research Consortium, Auckland, New

Zealand, January 2001.

Gitau, G.K., McDermott, J.J., Adams, J.E., Lissemore, K.D.,

Walter-Toews, D., 1994. Factors influencing calf growth and

Page 6: Use of pymarc as a nitrogen source for grazing dairy calves

J.M. Waweru et al. / Livestock Production Science 96 (2005) 233–238238

dairy weight gain on smallholder dairy farms in Kiambu

District, Kenya. Prev. Vet. Med. 21, 179 (190).

Griffin, S.C., 1974. Mammalian toxicology of pyrethrum. Pyreth-

rum Post 12 (2).

Gulbransen, B., 1974. Utilization of grain supplements by rough-

age-fed cattle. Proc. Aust. Soc. Anim. Prod. 10, 74–77.

Irungu, K.R.G., Kayongo-Male, H., Karue, C.N., 1981. Use of

pyrethrum marc for growing heifers. National Animal Husban-

dry Research Station. Naivasha and The University of Nairobi.

Julkunen-Titto, R., 1985. Phenolic constituents in the leaves of

northern willows: methods for the analysis of certain phenolics.

J. Agric. Food Chem. 33, 213–217.

Kanjanapruthipong, J., Leng, R.A., 1998. The effects of dietary urea

on microbial populations in the rumen of sheep. Asia-Aust. J.

Agric. Sci. 11 (6), 661–672.

Kitilit, J.K., Irungu, K.R.G., Kariuki, J.N., Indetie, D., Changwony,

K., 1996. Feeding sorghum silage and pyrethrum marc for

sustained growth of boran steers. Focus of Agricultural

Research for Sustainable Development in a Changing Economic

Environment. Proceedings of the 5th KARI Scientific Confer-

ence 14th–16th October, 1996. KARI Headquarters, Nairobi,

Kenya.

Malossini, F., Bovolenta, S., Piasentier, E., Piras, C., Martillotti, F.,

1996. Comparison of n-alkanes and chromium oxide methods

for estimating herbage intake by grazing dairy cows. Anim.

Feed Sci. Technol. 61, 155–165.

McDowell, L.R., 1985. In: McDowell, L.R. (Ed.), Nutrition of

Grazing Ruminants in Warm Climates. Academic Press,

Orlando, Florida.

Menke, K.H., Steingass, H., 1988. Estimation of the energetic

feed value obtained from the chemical analysis and in vitro

gas production using rumen fluid. Anim. Res. Dev. (Ger.) 28,

7–55.

Minson, D.J., 1982. Effects of chemical and physical composition

of herbage eaten upon intake. In: Hacker, J.B (Ed.), Nutritional

Limits to Animal Production from Pastures. CAB, Farnham

Royal, UK, pp. 167–182.

Mould, F.L., arskov, E.R., 1984. Manipulation of rumen pH and its

influence on the cellulosis in sacco, dry matter degradation and

rumen microflora of sheep offered either hay or concentrate.

Anim. Feed Sci. Technol. 10, 1–4.

Muiruri, H.K., Warui, C.M., Sum, K.S., 2001. Potential of

pyrethrum marc as a feed resource for poultry. The Challenges

of Drought to Livestock Production in Kenya. Proceedings of

the APSK 2001 Annual Symposium on 7–8 March at Egerton

University, Njoro, Kenya.

NRC, 1989. Nutrient Requirements of Dairy Cattle, 6th revised edn.

National Academic Press, Washington, DC.

arskov, E.R., McDonald, I., 1979. The estimation of protein

degradability in the rumen from incubation measurements weighed

according to rate of passage. Agric. Sci. Camb. 9, 499–503.

arskov, E.R., Hovell, F.D., Mould, F., 1980. The use of nylon bag

technique for the evaluation of feedstuffs. Trop. Anim. Prod. 5,

213–295.

Sinclair, L.A., Garnsworthy, P.C., Newbold, J.R., Buttery, P.J.,

1995. The effect of synchronizing the rate of dietary energy and

nitrogen release in diets with similar carbohydrate composition

and rumen fermentation and microbial protein synthesis in

sheep. J. Agric. Sci. Camb. 120, 251–263.

Spears, J.W., 1994. Minerals in forage. In: Fahey Jr., G.C.

(Ed.), Forage Quality, Evaluation and Utilization. National

Conference on Forage Quality, Evaluation, and Utilization,

Lincoln, pp. 281–317.

Statistical Analysis System (SAS), 1987. Guide for Personal

Computers, Version 6. Statistical Analysis Systems Institute,

Cary, NC, pp. 551–640.

Thomas, C., 1975. The value of pyrethrum marc as a supplement to

hay. Pyrethrum Post 14 (2), 53–55.

Underwood, E.J., 1981. Mineral Nutrition of Livestock, 2nd ed.

Commonwealth Agricultural Bureau, Slough, UK.

Van Soest, P.J., Robertson, J.B., Lewis, B.A., 1991. Methods for

dietary fibre, neutral detergent fibre and non-starch polysacchar-

ides in relation to animal nutrition. J. Dairy Sci. 74, 3588–3597.

Varma, A., 1991. Handbook of Inductivity Coupled Plasma Atomic

Emission Spectroscopy. CRC Press, Boca Raton, FL, p. 380.

Walshe, M.J., Grindle, J., Nell, A., Bachman, 1991. Dairy

development in Sub-Saharan Africa: a study of issues and

options. World Bank Technical Paper, vol. 135. Africa Technical

Department Series.

Williams, C.H., David, D.J., Lismaa, O., 1962. The determination

of chromium oxide in faeces sample by atomic adsorption

spectrophotometry. J. Agric. Sci. 59, 381–385.