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SID 5 Research Project Final Report

SID 5 (Rev. 3/06) Page 1 of 26

NoteIn line with the Freedom of Information Act 2000, Defra aims to place the results of its completed research projects in the public domain wherever possible. The SID 5 (Research Project Final Report) is designed to capture the information on the results and outputs of Defra-funded research in a format that is easily publishable through the Defra website. A SID 5 must be completed for all projects.

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Project identification

1. Defra Project code LS3310

2. Project title

Reducing the wastage in the dairy herd

Joint funded by MDC - project code 03/T4/04

3. Contractororganisation(s)

     Royal Veterinary College, Royal College StLondon,      NW1 0TU          

54. Total Defra project costs £ 321,092(agreed fixed price)

5. Project: start date................ 01 August 2003

end date................. 31 July 2008

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6. It is Defra’s intention to publish this form. Please confirm your agreement to do so...................................................................................YES NO (a) When preparing SID 5s contractors should bear in mind that Defra intends that they be made public. They

should be written in a clear and concise manner and represent a full account of the research project which someone not closely associated with the project can follow.Defra recognises that in a small minority of cases there may be information, such as intellectual property or commercially confidential data, used in or generated by the research project, which should not be disclosed. In these cases, such information should be detailed in a separate annex (not to be published) so that the SID 5 can be placed in the public domain. Where it is impossible to complete the Final Report without including references to any sensitive or confidential data, the information should be included and section (b) completed. NB: only in exceptional circumstances will Defra expect contractors to give a "No" answer.In all cases, reasons for withholding information must be fully in line with exemptions under the Environmental Information Regulations or the Freedom of Information Act 2000.

(b) If you have answered NO, please explain why the Final report should not be released into public domain

Executive Summary7. The executive summary must not exceed 2 sides in total of A4 and should be understandable to the

intelligent non-scientist. It should cover the main objectives, methods and findings of the research, together with any other significant events and options for new work.

Fertility in dairy cows has declined steadily over the past 40 years. The average UK cow survives only 3 lactations, with infertility the major cause for culling. The availability of heifers to enter the herd has therefore reduced at the same time that the demand for them is increasing. Once the heifers do enter the milking herd, the most profitable animals are those which can combine good milk production qualities with a regular calving pattern. The work presented in this report encompassed two related studies. The overall aim was to gain a better understanding of the causative factors which adversely affect fertility and hence longevity. The goal was to obtain information relevant to the British dairy industry that could be used by farmers to improve management practices and by breeders to implement better selection criteria. In the first study a group of 122 Holstein-Friesian heifer calves consecutively born on one farm in 2001 were monitored from birth until they were either culled or reached 5 years of age. For the second study we recruited 19 dairy farms to obtain a cohort of 24 consecutively born live heifer calves per farm (range 15-30). These provided a range of management practices representative of the UK. All kept Holstein-Friesian cows with a median herd size of 228 (range 105 to 540 cows). Calving records for all male and female calves born dead and alive (n=1097) were collected during the recruitment period and the remaining live heifer calves (n=509) were then monitored through to either culling or the end of the study (summer 2008). Profiles were obtained from each farm to identify key management practices.

Both studies followed the same general format, although sampling frequency was lower on Study 2. The reason and age at removal (death, cull or sale) for all animals were recorded. Calves were monitored throughout their life to obtain information on growth rates and to link this to metabolic indices measured in blood (insulin-like growth factor-I (IGF-I), insulin, glucose, non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHB) and urea). Further records of size, body condition score (BCS) and metabolic parameters were measured before and after each calving. Fertility records were obtained both as nulliparous heifers and in each lactation achieved. Milk records were obtained either from automatic recordings (Study 1) or milk records (Study 2). The first study therefore provided a detailed profile of each animal on a single farm where management was kept constant. The second study enabled us to investigate a larger number of animals and to assess the importance of management practices in addition to individual cow factors in determining the outcomes. Results of both studies are considered together.

Losses of cows occurred steadily throughout life. The overall incidence of perinatal mortality was 8%, but was much higher in primiparous cows (12%) and with twins (18%). Of those heifers born alive, 13-14% did not survive to their own first calving and so never produced any milk. Losses were mainly due to infection (up to 6 months), accident (6-15 months) or infertility/abortion (>15 months). These in turn

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were strongly influenced by the growth rates of the calves particularly over the first 6 months. Poorly grown calves at 1 month were more likely to die whereas those which were smaller at 6-9 months were less likely to conceive once the service period was reached at around 15 months. Even though the overall growth rate in Study 2 of 0.77 kg/d was close to industry recommendations, growth rates were extremely variable both within and between farms, ranging from 0.23 to 1.25 kg/d from 1-6 months for the 19 farms. This variability indicated that both management and individual calf factors were of importance. In relation to management, routine supplementation of colostrum, the subsequent use of milk replacer rather than whole milk and an ad libitum supply of milk all increased growth rates. Growth was reduced following gradual as opposed to sudden weaning and by dehorning after weaning. Slower growing calves from 1-6 mo increased their growth rate later but did not fully compensate so remained smaller at the start of the service period (range 209-498 kg at 15 mo). Growth rates throughout this period were highly correlated with the concentration of IGF-I. Calves from primiparous dams were born smaller but were able to compensate by rapid growth in their first 3 months.

Heifer fertility was better than cow fertility, with animals requiring 1.6 ± 0.01 services per conception (S/C) in Study 1 and 1.4 ± 0.1 S/C in Study 2. These figures, however, belied the fact that some animals in each group had very poor conception rates. This resulted either in culling (18/450 in Study 2, 4%) or very delayed age at first calving (AFC). In both studies the majority of animals had an AFC of 22-28 months but there was a long tail, extending up to 36 mo in Study 1, and with one animal not calving for the first time until 50 mo in Study 2. Detailed analysis of the results from Study 1 showed that, not only did late first calving increase the length of the initial non-productive period, but it was then followed by very poor performance in terms of both subsequent fertility and milk production, with only 2/9 cows surviving into a second lactation. In Study 1 early calving cows (AFC of 22-23 mo) had the highest survival over 5 years (86%), the greatest proportion achieving 3 lactations within that period (64%) and the highest proportion of their life spent in milk production (48%). Total milk production in 5 years was therefore also highest in this age group (AFC of 22-23 mo 25031±1491 kg, n=14; 24-25 mo 20395±1127 kg, n=61; 26-28 mo 16671±1335 kg, n=33; 32-36 mo 8029±2780 kg, n=9).

In relation to fertility in the first lactation, early calving cows in Study 1 did not require any more calving assistance and produced the lowest proportion (7%) of dead calves. They did, however, take 40 days longer to get back in calf than cows calving between 24-25 months and a similar trend was also found in Study 2. The average calving to conception interval in the first lactation in Study 1 was 147±10 days requiring 2.4±0.16 S/C with similar figures in Study 2 of 130±5 days and 2.3±0.1 S/C. In Study 1 21/118 (18%) of cows which calved once did not achieve a second lactation and in Study 2 the figures were 66/431 (15%). The main reasons for culling at this stage were calving problems, infertility and mastitis. In relation to fertility, this showed significant relationships with blood metabolic hormone concentrations around calving. High BHB concentrations before calving were associated with longer calving intervals, whereas higher IGF-I concentrations 1 week after calving were associated with a shorter calving interval. Heifers which failed to conceive again had higher insulin and lower glucose concentrations before calving, were often too fat and then lost more weight and BCS after calving. These results confirm our previous work in showing that the metabolic condition in which the animals calve is critical to their subsequent fertility. Comparison of the results from different lactations showed that the metabolic problems changed as the cows matured. By the third lactation in Study 1 milk production had increased significantly, more glucose was lost to the milk as lactose, so blood glucose concentrations after calving were lower and BHB values were higher. This was associated with a further decline in fertility from 46% to 26% conceiving to first service in lactations 1 and 3 respectively. Results of Study 1 showed that both insulin and IGF-I concentrations in the first 7 weeks after calving were moderately heritable (sire heritability estimates of 0.23 and 0.32 respectively) and IGF-I (but not insulin) concentrations were also significantly correlated between lactations. Study 2 found that IGF-I was highly correlated with growth rate. This suggests that selection for factors which influence blood IGF-I concentrations may influence both growth and fertility.

In conclusion good heifer rearing is absolutely crucial to the success of a dairy enterprise. Heifers which do not grow well in their first 6 months have poor fertility, calve late and produce less milk. Metabolic indices measured at 6 months are predictive of future fertility. Whilst there is clearly a genetic component to growth rate, management practices are also extremely important both to ensure adequate growth rates for all calves in a particular cohort and to minimise losses through either infection or infertility. Once animals reach calving it is then important to ensure that they are sufficiently mature without becoming fat in order to avoid enforced culling due to infertility in the first lactation. Breeding and raising cows for good fertility will benefit the financial success of the enterprise as farmers will achieve more milk per cow per year if a regular pattern of lactations is maintained. Enforced culling of young animals which have not yet reached their full milk production potential will also be minimised.

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Project Report to Defra8. As a guide this report should be no longer than 20 sides of A4. This report is to provide Defra with

details of the outputs of the research project for internal purposes; to meet the terms of the contract; and to allow Defra to publish details of the outputs to meet Environmental Information Regulation or Freedom of Information obligations. This short report to Defra does not preclude contractors from also seeking to publish a full, formal scientific report/paper in an appropriate scientific or other journal/publication. Indeed, Defra actively encourages such publications as part of the contract terms. The report to Defra should include: the scientific objectives as set out in the contract; the extent to which the objectives set out in the contract have been met; details of methods used and the results obtained, including statistical analysis (if appropriate); a discussion of the results and their reliability; the main implications of the findings; possible future work; and any action resulting from the research (e.g. IP, Knowledge Transfer).

Objective 1. To monitor the cohort of calves from CSA 6057/LS3636 through their first three lactations.

The results are presented according to Objective 1.4, combining data from all 5 years of the study to assess:

overall culling rate changes in fertility with age changes in metabolic profiles with age interrelationships between growth parameters, genotype and fertility

1.1 Methods1.1.1 Animals, Diet and Housing

Holstein-Friesian heifer calves (n = 122) from a single herd consecutively born between August and December 2001 were enrolled at birth and followed until either removal from the herd or 5 years of age. A further 12 animals were added to the study at first calving in 2003, giving a total study population of 134 animals. These heifers had 5 different sires, each responsible for between 20-31 offspring.

All calves were weighed at birth and given 2 litres of colostrum as soon as possible. Calves received 2 - 3 further feeds of 2 litres of colostrum via oesophageal tube prior to transport to the calf rearing unit. All animals were then placed in individual pens and reared on warm milk replacer reconstituted at 10% (37 oC, 2L twice daily, containing 16% oil and 22% crude protein (CP)). At 1 week old they were introduced to calf concentrate in the form of coarse mix (18% CP and 3 % oil). They were bedded on straw and had free access to water. Weaning occurred abruptly at 5 - 6 weeks and from then until turn out to pasture in April 2002 (at approximately 7 months of age) calves were group housed with others in the herd in slatted pens with sawdust bedding in group sizes of 30 animals based on bodyweight. They were fed to appetite until eating 2.5 kg/head/day beef concentrates (4.5% oil, 16% CP, 13% fibre, reached at about 14-16 weeks of age) when this concentrate level was capped. Any extra feed requirements were met by hay until 12 weeks of age, with maize silage introduced from 8 weeks of age. Heifers were group housed again (50 heifers per group, based on bodyweight) in October 2002 into cubicle yards with sand bedding. At this stage they were fed a 50:50 mix of grass and maize silage to appetite plus 1 kg/head/day beef concentrate and 100 g minerals. The average forage intake over this period was approximately 10 kg dry matter intake per day. The following spring the heifers had another period at pasture prior to calving.

At approximately 3-4 weeks prior to expected first calving, heifers were brought in and housed in cubicles where they were fed a transition total mixed ration (TMR) (Table 1.1). Following calving, animals were housed in cubicles and milked twice daily. Cows were fed a lactating TMR (Table 1.1) containing 54% grass silage, 19% maize silage, 2% hay and 25% concentrate mix containing minerals whilst they produced more than 30L milk/day.

Table 1.1. Dietary components for each ration fed

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Diet DM (%)

ME (MJ/Kg DM)

Crude Protein (% DM)

NDF (% DM)

Daily Intake (Kg DM)

Nulliparous Transition 54.3 9.2 12.0 46.4 10.0Lactating 03/04 55.5 11.9 16.5 34.0 21.0Lactating 04/05 46.3 11.8 18.6 38.5 25.0Lactating 05/06 46.4 11.6 13.8 36.5 25.0Lactating Transition 56.1 9.0 11.9 47.5 12.5

As their milk production decreased to below 30L/day, animals were turned out to pasture (spring and summer) or fed a low yield TMR. At drying off, animals were usually out at pasture (only thin animals received a supplemented ration) or fed a mixture of straw and grass silage in cubicles. At approximately 3-4 weeks prior to expected second calving, animals were again placed on a transition diet. This pattern was repeated for subsequent lactations. Dietary analysis for each year of the study is summarized in Table 1.1.

1.1.2 Reproductive Management

All animals were served by artificial insemination. Heifers were initially served at the first observed oestrus and any subsequent oestrus from the start of the service period (25 November 2001) until the end of March 2002. Pregnancy was confirmed by rectal palpation by the farm veterinary surgeon. If an animal was not pregnant at the end of this first insemination period she was turned out to pasture and reserved from July 2002 onwards. Following calving, animals were artificially inseminated at observed oestrus after a voluntary wait period of 60 days. Subsequent pregnancies were initially identified through the use of milk progesterone profiles and confirmed by rectal palpation.

1.1.3 Physical MeasurementsWeights and body condition scores (using a 0 to 5 scale of lean to obese with 0.5 intervals) were recorded

at approximately 1 week before expected calving and at weeks 1, 2, 4, 6, 8 and 12 postpartum for up to three lactations. The size and weight of each liveborn calf was recorded. Information on dead calves was obtained where possible. A calving assistance score was given at each calving defined as: 1, no assistance; 2, farm assistance; 3, veterinary assistance or 4, caesarean section. Due to the limited number of animals with higher calving assistance scores, all animals requiring any assistance were subsequently merged together for analysis.

1.1.4 Blood hormone and metabolite measurementsAs close as possible to 6 months of age (± 9 days) blood samples were collected via jugular catheter from

45 of the original cohort of 122 heifers to measure metabolic factors involved in the somatotrophic axis (insulin-like growth factor-I (IGF-I), insulin, glucose and growth hormone (GH), other metabolic indicators (non-esterified fatty acids (NEFA), urea and beta-hydroxybutyrate (BHB)) and cortisol. Serial blood samples were collected every 15 min between 08.00 h to 17.00 h. This sampling periodicity was determined by the pulsatile character of GH. The timing of sample collection for the other hormones and metabolites varied according to their secretion character in relation to the time of feeding (at 12.30 pm). Further details of sample collection times and assay methods are given in Swali et al. (2008). Subsequently blood samples were obtained by coccygeal venipuncture at approximately 1 week before expected calving and at weeks 1, 2, 4, 6, 8 and 12 postpartum for up to three lactations to measure IGF-I, insulin, glucose, BHB, NEFA and urea.

1.1.5 Milk Production MeasurementsAnimals were milked twice daily and milk yields were recorded automatically at each milking. These

figures were used to calculate overall lactation milk yield and days in milk (DIM) for each lactation. Figures were also calculated over the first 5 years of life. Total milk production, total DIM and the proportion of days alive spent in the milking herd were also calculated as DIM/days alive x 100%. The days alive were capped at the cow’s fifth birthday (1825 days) unless the cow had already died or been culled.

1.1.6 Reproductive MeasurementsNulliparous fertility was recorded as age at first service, age at conception and services per conception

(S/C). Cow fertility was monitored using milk progesterone profiles in samples taken twice weekly for 12 weeks after each calving. The profiles were used to determine the days to commencement of luteal activity (CLA) (first milk progesterone >3 ng/ml) and the length of the first luteal phase (number of days progesterone remained >3 ng/ml). The profile was typed into normal and abnormal, defined as delayed ovulation (DOV, >44 days with progesterone <3 ng/ml before CLA or >12 days with progesterone <3 ng/ml after CLA) and persistent corpus luteum (PCL, >19 days with progesterone >3 ng/ml, not following insemination) (see Taylor et al. 2003). Days to

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first service, days to conception and S/C in each lactation were also recorded. For cows which calved more than once, calving interval was obtained.

1.1.7 SurvivalThe age of culling or death and the primary reason why this occurred was recorded over the 5 years.

1.2. Results

1.2.1 Overall culling rateSurvival data for the calves which were recruited onto the original Defra study in autumn 2001 are given

in Table 1.2. This showed that 13% of the calves born alive never achieved a single lactation and so did not become productive.

Table 1.2. Survival data of original cohortNo. %

Recruited at birth in 2001 122Died/culled as juveniles before service 12 10%Aborted first pregnancy and culled 4 3%Calved at least once 106 87%Still alive in herd after 5 years 63 52%

Data from a further 12 cows was collected from first calving in 2003. These animals were not studied as juveniles as part of the original cohort but replaced those on the study which had been culled prior to calving. We therefore obtained culling data from first calving onwards for 118 cows. Of these 69 (58%) were still alive after 5 years. Primary reasons for culling were as follows: fertility n=12 (10%), calving related problem n=12 (10%), mastitis n=9 (8%), poor yield n=7 (6%), accident n=4 (3%), lame n=3 (3%), infection n=2 (2%).

Tracking the same group of animals in such detail over an extended period revealed a surprisingly complex web of events. Only a minority (48/118, 41%) of the cows which calved at least once succeeded in achieving an approximately annual calving interval and so calving 3 times within 5 years. Of the remainder, 21 cows (18%) only calved once and 49 (41%) calved twice during this period. Cows which failed to conceive or aborted during one service period were often maintained in the herd for considerable periods of time, resulting in some very long calving intervals.

1.2.2 Basic fertility parameters according to ageFertility data are presented by lactation number for convenience even though, as explained above, this did

not always relate very closely to the age of the animal (Table 1.3). Lactating cows required more S/C than the nulliparous heifers and the conception rate to first service decreased progressively as cows aged. The interval to the first progesterone rise after calving also showed a slight increase, whereas the length of the first luteal phase decreased. More cows had irregular progesterone profiles in lactation 2. Overall, however, the days to first service and calving to conception intervals did not vary between lactations.

Table 1.3. Comparison of fertility data according to lactation number NP heifers 1st lact 2nd lact 3rd lact P

n 111 110# 82 43Days to 1st service - 84 ± 3 89 ± 4 82 ±5 NSCalving to conception (days) - 147 ± 10 138 ± 10 148 ± 15 NSConception to 1st service (%) 59% 40% 38% 26% 0.05Services/conception (S/C) 1.6 ± 0.09 2.4 ± 0.16 2.3 ± 0.17 2.6 ± 0.27 0.05Days to 1st P4 rise (CLA) - 23 ± 2 26 ± 2 28 ± 2 0.05Length 1st luteal phase (days) - 21 ± 1 14 ± 1 9 ± 1 0.05No. (%) with abnormal P4 profile - 31% 63% 30%# includes 12 extra cows for which heifer fertility was not recorded

1.2.3 Effect of age at first calving (AFC) on subsequent fertility and productionAn earlier AFC can reduce rearing costs due to decreased feed, labour and building costs. Reducing AFC

too much may, however, increase the risks of dystocia as calving difficulties are influenced by the dam’s age, pelvic width and skeletal maturity which may be inadequate in dams calving at <24 months (Hoffman 1997; Hansen 2004). There is conflicting published evidence as to the effects of AFC on milk production. The actual

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AFC achieved is determined in part by management choice (age at the start of the service), combined with the reproductive efficiency of the nulliparous heifers.

In this study the majority of the 118 cows which calved at least once did so between 22-28 months of age (n=109). The remaining 9 cows calved between 32-36 months due to previous poor fertility or abortion. Overall AFC was strongly influenced by heifer fertility (Table 1.4).

Table 1.4. Nulliparous heifer fertility in relation to age at first calving Age at First Calving

22-23 mo 24-25 mo 26-28 mo 32-36 mo PNo. heifers 14 61 33 9Age at 1st service (days) 407 ± 4c 444 ± 2b 459 ± 5a 450 ± 12ab 0.001S/C 1.1 ± 0.07b 1.3 ± 0.07b 2.4 ± 0.22a 3.3 ± 0.3a 0.001No. conceiving to first service 13 (93%) 45 (74%) 9 (27%) 0 (0%) 0.001Age at conception (days) 408 ± 4d 451 ± 2c 503 ± 3b 740 ± 38a 0.001

Values are mean ± SEM; a > b > c > d; P < 0.05.

Fertility and production data relating to these AFC groups are summarised in Table 1.5. As might be expected the older calving animals had a greater pre-calving weight. This was associated with a higher BCS and a greater weight loss after calving. Despite the lower pre-calving weight of the youngest AFC group, the percentage of assisted calvings increased as AFC increased. Older calving cows also produced proportionately more dead calves. Cows with an AFC of 24-25 months had the best fertility in the first lactation. The 22-23 month AFC group had an average AFC of 43 days less than the 24-25 month AFC group and then took on average 40 more days to conceive in the first lactation. Both these groups therefore calved for a second time at an almost identical age. However the 2 older AFC groups both remained older at second calving. As AFC increased, proportionately fewer animals achieved a third calving within 5 years, reducing from 64% of the 22-23 month AFC group to none of the 32-36 month AFC group.

Table 1.5. Size, fertility and milk production parameters in relation to age at first calving  Age at First Calving

22-23 mo 24-25 mo 26-28 mo 32-36 mo PNo. cows 14 61 33 9SizeBirthweight (kg) 36 ± 2 36 ± 1 37 ± 1 34 ± 2 NSWeight at 9 months (kg) 256 ± 3 260 ± 3 259 ± 5 233 ± 9 0.05Actual AFC (days) 685 ± 3 d 728 ± 2 c 787 ± 4 b 1041 ± 12 a 0.001Pre-calving weight (kg) 591 ± 9b 621 ± 7b 625 ± 9b 769 ± 23a 0.001Weight loss postpartum 32 ± 14bc 26 ± 3b 6 ± 6c 59 ± 10a 0.001BCS pre-calving 2.1 ± 0.12 b 2.2 ± 0.07 b 2.3 ± 0.11 b 3.9 ± 0.12 a 0.001FertilityCalving assistance given # 2/12 (17%) 9/54 (17 %) 8/30 (27%) 6/9 (67%) 0.011No. dead calves 1/14 (7%) 10/61 (16%) 4/33 (12%) 5/9 (55%) 0.0111st service conception rate 5/14 (36%) 27/58 (46%) 10/33 (30%) 1/4 (25%) NSS/C 2.6 ± 0.52 2.2 ± 0.24 2.6 ± 0.32 4.7 ± 1.65 0.075Days open 180 ± 33 140 ± 13 135 ± 16 238 ± 99 NSFirst calving interval (days) 462 ± 33 414 ± 11 447 ± 22 432 ± 80 NSNo. cows reaching 2nd lact 14/14 (100%) 53/61 (87%) 28/33 (85%) 2/9 (22%)Age at second calving (days) 1147 ± 34b 1142 ± 11b 1233 ± 22a 1507 (n=2) 0.001No. cows reaching 3rd lact* 9/14 (64%) 29/61 (47%) 9/33 (27%) 0/9 (0%) 0.025Milk productionNo. cows still alive at 5 years (%) 12/14 (86%) 38/61 (62%) 16/33 (41%) 3/9 (33%) 0.039Total DIM for 5 years 861 ± 36a 714 ± 34ab 608 ± 40a 295 ± 94c 0.001Total 5 year milk yield (kg) 25031 ± 1491a 20395± 1127ab 16671 ± 1335b 8029 ± 2780c 0.001% life in first 5 yrs spent in milk 48 ± 1.9%a 42 ± 1.6%ab 38 ± 1.6%b 18 ± 0.5%c 0.001Values are mean ± SEM; a>b>c, P < 0.05. NS = not significant* Animals reaching third calving within 5 years of birth.

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Over the first 5 years of life the youngest calving animals produced the most milk overall because they had spent the greatest proportion of their life lactating and had overall good fertility and survival. The performance of the 9 late calving cows was particularly poor and only 2 of these animals conceived again. This late group tended to be slightly smaller at birth, were significantly lighter at 9 months of age but had become significantly heavier by the time they eventually calved. Due to their poor fertility and survival rates they produced less milk over 5 years, with the lowest proportion of their life spent in milk production (Table 1.5).

1.2.4. Changes in weight, BCS and metabolic profiles with ageData were compared from the 47 cows which began 3 successive lactations within their first 5 years of

life (Fig. 1.1). Blood metabolic profiles were monitored from 1 week before calving until 12 weeks into lactation. We believe this is the first time the same animals have been monitored in this way to investigate changes with maturity. Weight increased progressively with age. Body condition score loss was greatest in the first lactation but similar in lactations 2 and 3. IGF-I concentrations were higher in the first lactation and were significantly correlated in the early post partum period in the same cows between their first and second lactations (e.g. week 1, P<0.02; week 12, P < 0.01). Insulin concentrations fell after calving in lactations 2 and 3 but not in lactation 1 and showed little correlation between lactations. The third lactation cows had the lowest glucose concentrations and the highest BHB (not shown). This was associated with the highest milk production. The third lactation cows also had the worst fertility parameters (Table 1.5), suggesting that fertility suffers as milk yields increased with age.

Fig. 1.1. Metabolic changes according to lactation number for the same 47 cows.

500

650

800

-1 1 2 4 6 8 12

Week post partum

Wei

ght (

Kg)

Lactation 1Lactation 2Lactation 3

1

2

3

-1 1 2 4 6 8 12

Week post partum

Body

Con

ditio

n Sc

ore

0

30

60

90

-1 1 2 4 6 8 12

Week post partum

IGF-

I (ng

/ml)

0.15

0.3

0.45

-1 1 2 4 6 8 12

Week post partum

Insu

lin (n

g/m

l)

1.2.5 Juvenile growth and total milk production over the first 5 years Of the 134 animals recruited onto the study in total, 16 (12%) did not reach first calving, so produced no

milk. A further 6% died or were culled soon after calving (<55 days in milk). Only 44 cows (33%) completed 3 lactations within their first 5 years. Cows were subdivided according to total milk production over 5 years as follows: (1) <5000 Kg, n=9; (2) 5,000-10,000 Kg, n=21; (3) 10,000-15,000 Kg, n=22; (4) 15,000-20,000 Kg, n=50 and (5) >20,000 Kg, n=16. These subgroups were analysed with respect to their juvenile growth parameters and fertility data. The top producing animals were tallest at 3-6 months of age and heaviest at 9 months. They had good fertility as nulliparous heifers and therefore calved for the first time at the youngest age. The data suggest it may be possible to predict the most profitable animals based on early physical measurements.

1.2.6 Juvenile metabolic data and survival over 5 yearsEndocrine and metabolic traits were assessed at 6 months of age in 45 of the calves. These traits were not

significantly influenced by sire (n=5). Milk production and mortality records of these animals were obtained through 3 lactations. Seven of these heifers failed to achieve a lactation, 6 were culled after one, 17 after two and

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In all cases there was a significant (P<0.01) effect of lactation number

15 (33%) survived ≥3 lactations. Calves not achieving a single lactation had lower IGF-I at 6 months. Calves with higher glucose or BHB at 6 months were more likely to be culled after 2 lactations, an effect which was independent of yield (Table 1.6). Size and metabolic measurements of growing calves may therefore also prove useful in predicting longevity.

Table 1.6. Analysis of calf metabolite data at 6 months and 305 day milk yields according to the number of lactations which the animals later achieved (from Swali et al. 2008).

No. LactationsFactor 0

n=71n=6

2n=17

≥3n=15

Pa<b

IGF-I ng/ml 145 ± 6a 161 ± 6 156 ± 4 169 ± 5 b 0.03Fed BHB mmol/L 0.41 ± 0.074 a 0.45 ± 0.076 a 0.60 ± 0.041 b 0.47 ± 0.036 a 0.044Glucose mmol/L 4.8 ± 0.15 a 4.8 ± 0.13 5.2 ± 0.09 b 5.0 ± 0.09 0.081305 d milk yields (kg)First lactation 8332 ± 445 8000 ± 369 7857 ± 274 NSSecond lactation 9386 ± 338 9361 ± 276 NSThird lactation 10283 ± 355NS = not significant.

1.2.7 Effect of maternal ageEpidemiological studies in humans suggest that small size at birth is a predictor of some adult diseases.

Nutritional constraint experienced in utero may result in fetal adaptations which alter subsequent body structure and physiology. Size at birth is influenced by maternal age and parity. Most dairy cows are bred for the first time at about 60% of their mature body weight and therefore carry their first pregnancy whilst still growing. We hypothesised that this might alter the nutritional environment in utero and thus influence the development of the calf. We therefore used the data from our study to compare birth size, growth rates and fertility in consecutively born heifer offspring of 45 primiparous (PP) and 71 multiparous (MP) cows. Offspring of PP cows were significantly smaller at birth (weight, length, height, girth, P<0.01) than those born to MP dams. The ponderal index (weight/height3) was similar, showing that growth restriction was proportional. These differences were no longer apparent at 3 months, indicative of early catch up growth (Table 1.7).

Table 1.7. A comparison of the size measurements of heifer calves from primiparous (PP) or multiparous (MP) dams at birth and 3 months of age (from Swali & Wathes, 2007).

Calf age Dam n Weight (kg) Length (cm) Height (cm) Girth (cm) PI#(Kg.m-3)

Birth PP 45 34 ± 0.9a 84 ± 1.3a 76 ± 0.8a 80 ± 0.4a 78 ± 2.3

MP 71 37 ± 0.6b 89 ± 1.0b 78 ± 0.6b 82 ± 0.3b 80 ± 2.1

P 0.000 0.001 0.017 0.000 0.579

3 months PP 40 95 ± 2.7 108 ± 1.1 90 ± 0.6 109 ± 1.0 128 ± 2.8

MP 69 98 ± 1.7 108 ± 0.7 91 ± 0.5 109 ± 0.7 128 ± 1.8

All values are the mean ± SEM. Differences in size were only apparent at birth, a<b.#The ponderal index (PI) was defined as weight/height3.

The PP offspring conceived more rapidly during their first service period as nulliparous heifers (P<0.02) and fertility in the first lactation followed a similar trend although differences were not significant (Fig. 1.2). Having a primiparous dam did therefore result in a smaller size at birth but despite this fertility was generally better in offspring of PP than MP dams.

1.2.8 Effect of maternal age and milk yield during pregnancyIn MP cows fetal development competes for nutrients with concurrent milk production, which increases as cows mature. Data from the study were therefore analyzed to test the hypotheses that (a) maternal age and milk yield during pregnancy alter calf birth size and (b) birth weight in calves born to MP dams influences subsequent productivity and fertility. Heifers with multiparous dams and 3 sires were monitored from birth to the end of their first lactation to assess effects of birth weight on growth, milk production and fertility. Calves were analyzed as 3 subgroups: low (L), average (A) and high (H) birth weight (BW) calves (n = 21-22 per group) (Swali & Wathes, 2006).

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Fig 1.2 Effect of maternal age on fertility of offspring: (a) nulliparous heifers and (b) primiparous cows

5 10 15 20 25 30 35 400

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LBW calves were born 10 kg lighter than HBW calves and remained significantly lighter throughout the study. They were also generally smaller in other measured indices (length, height, girth, ponderal index) between birth and 9 months. Pearson correlations showed significant relationships between most size parameters (height, weight and girth) measured at 3, 6 and 9 months of age, but not with size at birth which is more strongly influenced by uterine environment than by genetic potential.

The LBW calves were more likely to have older dams (lactations 3-6) with higher peak yields (>42 kg/day). Across all groups dam milk production also affected birth height, which was lower in calves whose dams had a high peak yield (Table 1.8). The offspring of older dams (>1 lactation) remained smaller before calving, had lower pre-calving insulin concentrations and a lower postpartum BCS (Table 1.8). Analysis according to the 3 birthweight groups found that milk production parameters were indistinguishable (not shown) and other metabolic parameters (IGF-I, glucose) measured around first calving were also unaffected. HBW offspring were more likely to have persistent corpora lutea following their first calving and other fertility parameters also tended to be worse.

Table 1.8. Summary of dam factors which had significant effects in mixed model analyses of birth size, metabolic and fertility traits of the offspring (from Swali & Wathes, 2006)

Dam factor Dependent variable* P Regression ratio305d milk yield Birth height 0.009 0.002Peak milk yield Birth height 0.024 -0.362

Lactation No.+ 1 (n = 21) >1 (n = 32)Pre-calving weight (kg) 0.004 664 17 606 8Pre-calving insulin (ng/ml) 0.043 0.42 0.037 0.36 0.019BCS weeks 8-12 postpartum§ 0.044 7.6 0.63 5.8 0.35Days to 1st service as PP cow 0.028 90 6.7 84 4.5

*The dependent variables tested included all the birth size measurements, fertility measurements made as nulliparous (NP) heifers and as primiparous (PP) cows, and the weight, BCS and metabolic measurements made around calving.+ Lactation number was analysed according to whether the dam was in her first (=1) or later (>1) lactations during the pregnancy. Values are mean SEM.§ Measured as the area under the curve (AUC) for weeks 8-12 after first calving.

The results support the hypothesis that high milk production in the dam may predispose to birth of a smaller calf. Smaller birth size did not, however, have any subsequent adverse effects on productivity in the first lactation as sire was more influential on milk production at this stage.

1.2.9 Heritability analysisSire heritability estimates were calculated for the fertility, size and metabolic traits measured around first

calving in the offspring of the MP dams and for their first lactation milk production. This confirmed previous reports (eg Coffey et al. 2003) in showing that BCS around calving in the first lactation were heritable traits in addition to the expected effects of sire on milk production parameters. In addition we showed that weight, IGF-I and insulin concentrations after first calving and fertility in the first lactation were all moderately heritable (Table

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1.9, Swali & Wathes 2006). The heritability of IGF-I is of particular interest as we have shown previously that IGF-I concentrations around calving are predictive of fertility (Taylor et al. 2004).

Table 1.9. Estimates of sire heritability for traits measured around first calving in the heifer offspring of 3 different sires+(from Swali & Wathes 2006).

Trait Pre-calving Weeks 1-7 postpartum Weeks 8-12 postpartum

Weight ND 0.73 0.75BCS 0.11 0.10 0.01IGF-I ND 0.23 0.04Insulin ND 0.32 0.43Glucose ND ND ND

Fertility Milk productionAge at 1st service as NP heifer 0.33 Peak yield 0.35Days to 1st P4 rise as PP cow 0.12 305d yield 0.30Days to 1st service as PP cow 0.77 Fat % weeks 1-20 0.25Days to conception as PP cow 0.34 Protein % weeks 1-20 0.84Age at conception as PP cow 0.05

ND = not detectable, sire variance < 0.01NP = nulliparous, PP = primiparous+Sires had 28, 20 and 16 daughters respectively in this study

Objective 2. To determine the relative importance of genetic and environmental components during the rearing period in relation to subsequent cow fertility and longevity.The original objectives were summarised as follows:

Recruit approximately 500 Holstein type heifers at birth from a selection of UK dairy farms and obtain details of birth parameters and genotype.

Obtain size and blood metabolite measurements from these animals at approximately birth, 6 months and 15 months of age.

Obtain information from each farm involved on their calf rearing policy. Obtain fertility data of the nulliparous heifers. Investigate the relationships between metabolic status, milk production, fertility and the timing and

reasons for culling during the first lactation.

2.1 Methods2.1.1 Animals and Farms

We recruited 18 commercial dairy farms and 1 primarily research farm across southern England onto the study between August 2003 and October 2004. These farms provided a range of management practices representative of those commonly encountered in the UK. All kept Holstein-Friesian cows with a median herd size of 228 (range 105 to 540 cows). The recruitment period for each individual farm generally lasted from 1 to 4 mo during the main calving season, with the aim of obtaining a cohort of approximately 25 consecutively born live heifer calves per farm. The research farm provided three groups of calves, with each group on a different milk feeding regime (milk replacer fed warm ad libitum (mean daily intake 14L), cold ad libitum (mean daily intake 11L) and restricted feeding (warm 2L fed twice daily). This ultimately gave a total of 21 cohorts of calves with a mean cohort size of 24 (range 15-30). These calves were the offspring of 94 sires (range 1-32).

Calving records for all male and female calves born dead and alive (n=1097) were collected during the recruitment period on each farm from on-farm calving records. The remaining live heifer calves (n=509) were then monitored through to summer 2008. For heifers failing to reach their first lactation, the reason and age at removal (death, cull or sale) was recorded. Losses on each farm were then calculated for 5 lifetime phases as follows:(1) Perinatal: stillbirths and mortality within the first 24 h of life of male and female calves. This was calculated by dividing the number of dead calves at 24 h after birth by the total number of calves born on the farm during the recruitment period.

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(2) Neonatal: the number of female calves that died between 24 h and 28 d of age divided by the total number of females alive at 24 h. (3) Calf: the number of female calves that died or were culled between 1 and 6 mo of age divided by the total number of females alive at 1 mo.(4) Heifer1: the number of heifers that died or were culled between 6 mo and the commencement of breeding, divided by the total number of heifers alive at 6 mo. These animals were never inseminated or run with the bull. (5) Heifer2: the number of heifers that died or were culled between the commencement of breeding and first calving divided by the total number of heifers served.

2.1.2 Farm-level risk factorsUsing a standardised data capture template, data on the feeding strategies and housing systems of the

calves for each farm were collected by means of an interview with the farmer or herdsmen during scheduled farm visits to obtain a series of detailed farm profiles. Information recorded included the routines for housing and feeding the pre-weaned calf (including details on colostrum feeding), weaning policy, and the post-weaning management of the calves. For each factor a category was established to represent the best practice for a particular management practice or husbandry technique, and 1 or 2 categories were assigned to represent the extremes based on published calf management guidelines (Heinrichs and Radostits, 2001; Roy, 1990).

2.1.3Heifer-level risk factors During the recruitment period information recorded included date of calving, dam parity at calving,

calving ease (unassisted or assisted), calf gender (male or female), and calf number (twin or singleton). Date of calving was subsequently used to assign a season of calving: winter (December through to February), spring (March through to May), summer (June through to August), and autumn (September through to November). All live heifer calves were assessed at approximately 1, 6 and 15 mo of age to measure size and metabolic parameters. Body weight (WT) was measured using a portable weigh platform with Tru-Test loadbars connected to an Eziweigh 2 indicator (Ritchey Tagg, North Yorkshire, UK). Heart girth (GIRTH) and crown-rump length (CRL) were measured using a tape measure and height at withers (HT) was measured using a height stick. Blood samples were collected for determination of plasma IGF-I, insulin, glucose and urea concentrations.

2.1.4 Heifer breeding managementAt the start of the breeding period at a mean age of 16 ± 0.2 mo, breeding details were collected for

heifers. Breeding methods included artificial insemination (AI) only (n=218), natural service only (n=117), embryo transfer only (n=12) or a combination (n=33). Where AI only was used, the date of each insemination and the number of inseminations per conception were recorded. For animals run with a bull, the length of time heifers were with the bull was recorded. We also noted information on date of pregnancy diagnosis and conception. For heifers failing to conceive (FTC) the total number of services given to each animal, and the number of times run with a bull before removal from the herd was recorded. For all animals this information was used to calculate age at first service (AFS), number of services per conception (S/C), first service pregnancy rate, and age at first calving (AFC).

2.1.5 Collection of first and second lactation dataFor all animals reaching calving, GIRTH, HT and BCS were measured pre-calving, and BCS was also

recorded at wks 1 and 8 after calving. Blood samples were collected pre-calving, and postpartum at wks 1 and 8, for the analysis of IGF-I, insulin, glucose, urea and BHB. Milk samples were also collected for up to 10 wks postpartum and analysed for progesterone. The number of days from calving to first service, method of insemination, number of S/C, first service pregnancy rate, and the number of days from calving to conception was recorded for all animals that were served. For all animals that calved for a second time (within the time frame available for the project), the calving interval (CI) was recorded. The number of animals not served post-calving for health or other reasons, and those which FTC despite services was also noted. For all heifers that entered their first lactation, milk production data were recorded, including days in milk (DIM), total milk production, milk production per d, and 305 d milk yield, using farm records and milk recording certificates.

This sampling and data collection protocol was repeated at second calving for all those animals which had reached this point by July 2007 (sampling) and August 2008 (data collection).

2.1.6 Data AnalysisThe influence of variables at the farm and heifer level on perinatal mortality were analysed by binary

logistic regression using Stata 9.2 and a multilevel modelling approach. Odds ratios (OR) were calculated where an OR>1 indicated an increased outcome likelihood as the explanatory factor increased, after adjusting for other variables, whereas an OR<1 indicated that the odds of the outcome decreased with the explanatory factor. The

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effect of the farm and heifer level variables on survival were determined using survival analysis in SPSS 15.0. Farm was used in the analysis as a covariate. When testing the heifer-level variables, actual age at measurement was used as a covariate. Survival data were also analyzed using the Cox proportional hazards regression model. For each independent variable in the model, a hazard ratio (HR) and their corresponding 95% confidence intervals was calculated.

Multivariable multi-level regression analysis was used to investigate the effect of a number of farm and heifer level factors on growth, using Stata. A random effects regression model (two-level model) was used to include the two sources of random variation in the data: (i) the variation between the heifers within each farm, and (ii) the variation between farms. Because of the variability in the exact age of heifers at 1, 6 and 15 mo, actual age at measurement was forced into each model as a covariate when considering the effect of the heifer-level variables on growth rate. Coefficient values were calculated that indicated if growth per d increased or decreased, as the explanatory variable increased by one unit, after adjusting for the other variables in the equation.

2.2 Results2.2.1 Farm management profiles

This section summarises information obtained relating to the calf rearing conditions on the different farms used in the study. Calves were left alone to suckle colostrum from the dam on 4 farms; colostrum was routinely fed to the calf via a teated bottle, bucket or oesophageal tube on 8 farms, with 7 farms giving assistance only if suckling was not observed. Supplemental colostrum (pooled or frozen colostrum) was given to calves on 12 farms; on the remaining farms calves received colostrum from their dam only. The volume of colostrum fed to calves was unknown on approximately half of the farms; the remaining farms either gave calves ≤3L (n=4) or >3L (n=4). Most farms fed colostrum to calves for 1 to 4 d; 3 farms fed colostrum for <24 h and 4 farms fed colostrum for at least 7 d (up to 42 d on 3 farms).

During the pre-weaning period all farms, except one which used individual outdoor hutches, kept calves indoors in either single pens (n=7), group pens of ≤6 (n=6), or group pens of >6 (n=5). Most farms fed calves twice daily with either whole milk (n=8) or milk replacer (n=6), with some farms using a combination of the two (n=5). Most farms fed calves ≤5L milk/d, whilst a few fed calves >5L milk/d (up to 10L) under a restricted feeding regime (n=3 cohorts) or ad libitum milk feeding (n=4 cohorts). Farms generally fed warm milk (n=17), with milk temperature being routinely checked on just under half of the farms (n=7). Most farms (n=14) made concentrates (crude protein (CP) range 14-22 %) available to calves within the first week of life; concentrates were given to the calves on the remaining farms from d 8 to 28.

The majority of farms (n=13) dehorned calves before weaning. Farms weaned calves either abruptly (n=9) or by reducing milk feeding to once a day for approximately 1 wk before weaning (n=10), when calves were generally >6 wk old (n=15). Most farms based weaning on a combination of weight, feed intake and age (n=13), and weaned calves in their original pens (n=18). Following weaning half of the farms moved calves immediately to their new housing, and most farms grouped calves according to age (n=11) in groups of 7-20 (n=9), or >20 (n=7). Few farms housed calves in groups of ≤6 after weaning. The majority of farms (n=12) fed concentrates post-weaning until approximately 6 mo of age at restricted rations of ≤3kg/d (CP range 14-18 %).

2.2.2 Incidence and causes of calf mortality Perinatal mortality (stillbirths and mortality within the first 24 h of life) of male and female calves

combined was 7.9%, and for female calves it was 6.4%. The range was 2.7–14.3% between farms (Table 2.1). This figure was significantly higher in cases where calving assistance was required (19.1% v 5.6%, OR 4) and in twin births (18.5% v 7.0%, OR 3), and was lower in multiparous versus primiparous dams (12.1% v 5.6%, OR 0.4). Herd size (<200 cows; 8.6%, 200-400 cows; 7.9% and >400 cows; 7.4%, P=0.6) and season of calving (winter 11.5%, spring 9.5%, summer 8.4% and autumn 6.8%, P=0.4) were not associated with the incidence of perinatal mortality. Although a numerically greater proportion of male calves were born dead or died within 24 h, this difference was not significant (males 8.8%, females 6.4%, P=0.3).

On average 6.8% of heifers died or were culled between 1 d and 6 mo of age. This figure was influenced by milk feeding, group size and weaning management: mortality was increased if weaning time was based solely on age, by moving at weaning and by dehorning after weaning. Low WT and IGF-I concentration at 1 mo was associated with reduced subsequent survival up to 6 mo: mean IGF-I concentration at 1 mo for calves that survived to 6 mo of age was 43 ng/ml, compared to 21 ng/ml for calves that died between 1 and 6 mo (P<0.01). Insulin, glucose and urea concentration at 1 mo, dam parity, and calving ease were not significant risk factors for calf mortality.

Between 6 mo and first calving a further 7.7% of heifers either died (42%) or were culled (58%); accidents and infectious disease accounted for the majority of calf deaths between 6 and 15 mo, whilst infertility (18 of 450 animals served, 4.0%) was the main reason for culling following the start of the first service period.

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Ten of these animals received a mean of 3 ± 0.7 serves (range 1-9) over a period of up to 427 d. Six animals were run with a bull for about 4 mo but FTC, whilst 2 were put with a bull following failure to conceive to AI, and again FTC. Two heifers culled at this stage for infertility were diagnosed as freemartins; in total 10 heifers were culled as freemartins, 8 at birth (8 of 494 females born alive, 1.6%), 2 around service. Eleven heifers suffered late embryonic mortality (EM) following a positive pregnancy diagnosis. All 11 were re-served and subsequently successfully calved for the first time. Six heifers aborted during their first gestation (days pregnant 188 to 257 d): of these 4 started a lactation and entered the milking herd whereas 2 were culled.

Overall 14.5% of potential replacement heifers died or were culled before first calving ranging from 0 to 29% on individual farms.

Table 2. 1. Summary of number and percentage of dairy heifers failing to reach first calvingMortality Description Mean (n) Range between farmsPerinatal Stillbirths & mortality within 1st 24h of life of

male & female calves 7.9%(87/1097)

2.7 - 14.3%

Neonatal Female calves that died between 24h & 28d 3.4%(17/494)

0 - 12.1%

Calf Female calves that died or were culled between 1 & 6 mo

3.4%(17/506)

0 - 28.6%

Heifer1 Heifers that died / culled between 6 mo & the commencement of breeding

3.5%(17/489)

0 - 18.5%

Heifer2 Heifers that died / culled between the commencement of breeding & 1st calving

4.2%(19/450a)

0 - 21.1%

Total live born heifers failing to calve for 1st time 14.5% 0-28.6%a22 heifers sold on one farm as a farm management decision, so heifer2 mortality figure is based on 450 heifers.

2.2.3 Heifer growth ratesThe daily growth rate in each size parameter (WT, GIRTH, HT, CRL) was calculated between 1-6 and 6-

15 mo. The mean daily weight gain up to 6 mo of age was 0.77 kg/d, with extreme variability between calves both between farms (mean range 0.23 to 1.25 kg/d) and within animals in the same herd (eg individual range on one farm 0.45 to 1.13 kg/d). Daily weight gain remained consistent at 0.75 kg/d from 6-15 mo but average daily change in GIRTH, HT and CRL from 6-15 mo was significantly less (P<0.001) compared to that from 1-6 mo (approximately 50% lower growth). Calves with greater values of WT, GIRTH, CRL and HT at 1 mo showed a higher rate of daily WT gain from 1-6 mo but slower skeletal growth (GIRTH, CRL and HT) (P<0.1-0.001). Differences in growth rates resulted in considerable differences in the sizes reached at 15 mo of age. For example, WT ranged from 209-498 kg and HT from 104-141 cm (Table 2.2).

Table 2.2. Summary of size parameters of heifers during the rearing period; 1 mo (n=506), 6 mo (n=489) and 15 mo (WT n=450, GIRTH, HT and CRL n=432).

Variable Age (mo) Mean SEM Minimum MaximumWT (kg) 1 56 0.7 25 102

6 175 1.7 84 27415 373 2.4 209 498

GIRTH (cm) 1 89 0.4 70 1256 131 0.4 102 15415 174 0.5 147 212

HT (cm) 1 80 0.2 62 936 104 0.3 85 12315 126 0.3 104 141

CRL (cm) 1 94 0.4 67 1246 134 0.5 100 16815 169 0.5 128 201

Farm level factors influencing growth rates included season of calving, milk volume and type, weaning method and group size. For example, calves born during the winter months had lower average daily CRL gains than those born in other seasons (P<0.01). Calves on farms that received fresh or frozen pooled colostrum in addition to that from their own dam had a significantly increased mean daily HT gain than calves on farms that fed calves colostrum from their dam only. The daily change in HT of calves on farms that always assisted colostrum feeding was on average 0.03 cm/d more than calves on farms that left the calf alone with the dam (P<0.05). After editing the dataset to include only farms that fed a known volume of colostrum (≤3L or >3L), daily weight gain of calves on farms feeding >3L was on average 0.17 kg/d greater than calves on farms fed ≤3L colostrum (P=0.055).

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Type of milk fed was significantly associated with growth rate; growth in all size parameters of calves on farms that used milk replacer only was significantly higher compared to calves fed whole milk only (P<0.05-0.001). For example, daily weight gain of calves fed milk replacer only was on average 0.16 kg/d more than calves on farms using whole milk only (P<0.05). As expected, mean daily weight and HT gain for calves on farms offering milk ad libitum was significantly more (on average 0.21 kg/d and 0.03 cm/d respectively) than calves on farms fed restricted volumes (P<0.01).

No significant associations between growth and housing type (single indoor pen, outdoor hutch or group pen) were observed, however calves on farms housing animals in groups of >6 before weaning grew on average 0.15 kg/d less than calves on farms that grouped animals in pens of ≤6 (P<0.05). Weaning method was important. Calves on farms where milk feeding was gradually phased prior to weaning had a significantly reduced daily WT gain (P<0.05), and tended to have a reduced daily GIRTH and HT gain compared to calves on farms where weaning was abrupt (P<0.1). Average daily change in WT, GIRTH and HT was significantly lower for calves on farms that dehorned animals after compared to before weaning (P<0.01). For example, daily weight gain was on average 0.17 kg/d less (P<0.05). Calves kept in groups of >20 after weaning had significantly higher average daily change in WT, GIRTH and CRL than calves housed in groups of ≤6 (P<0.05).

No clear associations between the farm level variables and growth from 6-15 mo were found, indicating that the management of calves during the first few months of life was not associated with growth over this period. However, calves with greater body size at 6 mo showed a reduced average daily change in GIRTH, CRL and HT from 6-15 mo (P<0.05-0.001).

2.2.4 Relationships between size and growth of heifers with metabolic indicesThese growth parameters were associated with several of the metabolic indices. Circulating IGF-I

concentration was significantly associated with growth throughout the rearing period. For example, for every 1 ng/ml increase in IGF-I concentration at 1 mo, mean daily change in WT (P<0.001), GIRTH (P<0.1) and CRL (P<0.01) from 1-6 mo increased. By 6 mo IGF-I concentration was positively associated with all measures of body growth (P<0.001). IGF-I concentration at 6 and 15 mo was positively associated with daily weight gain from 6-15 mo (P<0.05-0.001). Calves with more rapid daily gains in GIRTH (P<0.001) were associated with higher insulin concentrations at 6 and 15 mo. Calves with a greater average daily change in WT, GIRTH, CRL and HT from 1-6 mo also had higher glucose concentrations at 6 mo (P<0.01-0.001). Increased urea concentration at 1 mo was associated with reduced daily gain in GIRTH (P<0.05), but at 6 mo increased urea concentrations were associated with increased daily GIRTH (P<0.05) gain from 1-6 mo.

Large calves at 1 mo had a greater WT gain up to 6 mo than small calves. Calves were analysed with respect to their daily weight gain from 1-6 mo. The slowest growing calves (<0.6 kg/d) were of average WT at 1 mo (55.8 ± 1.7 kg). Calves with medium growth rates of 0.6-0.8 kg/d were on average 6 kg lighter at 1 mo than those which subsequently grew more rapidly (>0.8 kg/d) (Fig. 2.1a). By 6 mo the differences in growth rates from 1-6 mo resulted in major differences in WT (129, 165 and 207 kg respectively for daily gains of <0.6, 0.6-0.8, and >0.8 kg/d P<0.001). The effect of growth rate from 1-6 mo on WT remained significant at 15 mo, although the differences were substantially less than those recorded at 6 mo (339, 368 and 393 kg respectively, P<0.001). Daily weight gain from 1-6 mo was positively correlated with WT gain from 6-15 mo (r=0.2, P<0.001). Although the slower growing calves increased their growth rate, this still remained below that of the other two groups at 6 mo. However the very rapidly growing calves decreased their growth rate from 6-15 mo. These differences were again closely associated with the IGF-I concentrations; the most rapidly growing calves had significantly higher IGF-I concentrations at both 1 and 6 mo and this difference remained at 15 mo (Fig. 2.1b).

In summary, sub-optimum growth of some heifers within each cohort was established at an early age and resulted in animals which reached the start of the service period at an inadequate size (WT range 209-498 kg at 15 mo).

Figure 2.1. Mean (a) daily WT gain and (b) IGF-I concentration, according to WT gain from 1-6 mo.

(a) a<b<c, P<0.001; d<e, P<0.001 (b) a<b, P<0.001; c<d<e, P<0.001; f<g, P<0.01

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e g f f d b a c a

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2.2.5 Nulliparous fertilityOf the 509 heifers recruited, 450 survived to the start of breeding (died/culled n=37, sold n=22), and were

served at least once. Of these, 18 FTC and 1 animal died from pneumonia shortly after service so was excluded. Of the 431 heifers calving for the first time, 11 heifers suffered late EM following a positive pregnancy diagnosis and were served again prior to first calving and 6 heifers aborted during first gestation (days pregnant 188 to 257 d) and entered their first lactation. Data from heifers that had late EM or aborted during first gestation were excluded from the subsequent analysis. Farm policy on one herd was to calve all heifers for the first time at 3 years old so fertility data for this cohort of 22 heifers was also excluded. Therefore the nulliparous fertility analysis was based on a dataset of 392 animal records. Mean AFC for each group of heifers that calved is summarized in Table 2.3.

Table 2. 3. Age in days at first calving (AFC) for all animals that calved for the first time (n=431) n Mean AFC ± SEM Range AFC

1. Conceived + calved 392 791 ± 6ac (26 mo) 636 – 1529 (21-50 mo)2. Conceived, EM, re-served + calved 11 978 ± 44b (32 mo) 775 – 1256 (22-41 mo)3. Conceived, aborted + entered 1st lactation 6 698 ± 20ad (23 mo) 634 – 782 (21-26 mo)4. Calved as 3 year olds 22 1096 ± 4b (36 mo) 1075 – 1157 (35-38 mo)Total 431a<b P<0.01; c>d P<0.05

Mean AFC for heifers that conceived and calved was 26 mo, which was significantly greater than heifers that aborted and started their first lactation at 23 mo. Heifers that suffered late EM and were re-served before calving calved for the first time at a similar age (33 mo) as heifers with a target AFC of 3 yrs. Most heifers calved at an age of 670 to 850 d (22 to 28 mo), with a small proportion of cows calving at <22 mo and >28 mo (Fig. 2.2). The mean AFC varied by over 200 d between farms from 708 ± 7 d to 959 ± 43 d (excluding the late calving herd). Measures of fertility for the nulliparous heifers that conceived and calved are summarized in Table 2.4.

Table 2.4. Measures of nulliparous fertility for 392 heifers which successfully conceived and calved

na Mean ± SEM RangeAge at 1st service (AFS, days) 354 473 ± 5 357 – 936 (12-31 mo)Number services per conception (AI only) 200 1.4 ± 0.1 1 - 5Number services per conception (AI/Bull/ET)b 134 1.3 ± 0.1 1 - 6Pregnant to first servicec (%) 200 67% (133/200)AFC (days) 392 791 ± 6 636 – 1529 (21-50 mo)aA total of 392 heifers conceived and calved, but service details were incomplete at the farm level for some animals. bAI=artificial insemination; Bull=natural service; ET=embryo transfer. cAI services only.

Figure 2.2 Histogram of frequency of AFC in days for all 392 heifers that conceived and calved

SID 5 (Rev. 3/06) Page 17 of 26

Age (months)

BW

gai

n (k

g/d)

BW gain (kg/d) from 1-6 mo

IGF-

I (ng

/mL

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c e d b e

a

Size parameters and blood metabolite and hormone levels at 1, 6 and 15 mo, and BCS at 15 mo were considered as factors associated with the fertility of nulliparous heifers. Growth rate in each parameter before (1 to 6 mo) and during/after (6 to 15 mo) puberty was also considered. Large body size and increased IGF-I concentration in calves at 1, 6 and 15 mo was associated with a reduced AFS (P<0.001-0.1). Mean AFS was reduced by 110 d with every 1 kg/d increase in WT gain between 1 and 6 mo (P<0.001), and by 167 d with every 1 kg/d increase in WT gain between 6 and 15 mo (P<0.001). Increased glucose concentration at 6 mo was also associated with a younger AFS; for every 1 mmol/l increase in glucose concentration at 6 mo, AFS was reduced by 25 d (P<0.01). Insulin and urea concentrations during the rearing period were not associated with AFS.

Growth rates between 1 and 6 mo were not associated with the number of S/C but faster growing heifers in WT between 6 and 15 mo required more S/C (P<0.05) than heifers that grew more slowly over this period. Increased CRL at 1 mo and WT at 15 mo were associated with an increased number of S/C (P<0.05). IGF-I and insulin concentrations during the rearing period did not have a significant impact on S/C. Heifers requiring ≥3 S/C tended to be younger at first service (mean 430 d) than heifers pregnant to first service (mean 467 d). The 18 heifers which were culled as a result of infertility had a mean AFS of 16.2 ± 0.7 mo, and received between 1 to 9 services.

Increased WT and IGF-I concentration at 1, 6 and 15 mo was associated with a reduced AFC (P<0.001-0.01); heifers calving at >25 mo of age tended to be lighter and had lower IGF-I concentrations at 1, 6 and 15 mo. Heifers with high glucose concentrations at 6 mo were younger at first calving (P<0.05). Higher growth rates in all parameters between 1 and 6 mo, and greater weight gain between 6 and 15 mo were therefore associated with a younger AFC.

Despite this generally positive effect of a large size, heifers which FTC tended to be heavier at 6 mo (P<0.1); this difference was significant by 15 mo (395 vs. 366 kg, P<0.05). With every 1 kg increase in WT at 15 mo, heifers were more likely to FTC (OR=1.02, 95% CI=1.00-1.03, P<0.05). The skeletal measures of CRL and HT did not, however, differ between heifers which did or did not conceive. Animals FTC had significantly higher insulin concentrations at 1 mo (P<0.05) and tended to have higher glucose concentrations at 15 mo (P<0.1).

2.2.6 Fertility in the first lactationA total of 431 of the starting population of 509 heifers calved at least once. Of the 431 heifers that calved,

404 survived to the start of breeding, and were served at least once at a mean of 82 ± 1.6 d (ranging between 31 and 297 d across farms) after first calving. Of 431 animals that calved, 66 (15%) animals were removed from farms during their first lactation (27 before breeding, and 39 after). The main reason for disposal following first calving was infertility (n=17, 26%), followed by mastitis and udder related reasons (n=11, 17%), and lameness and skeletal reasons (n=8, 12%). Twenty five heifers suffered late EM following a positive pregnancy diagnosis and were served again: of these 6 were subsequently culled and 19 calved or are due to calve for a second time. Eight heifers aborted during second gestation (days pregnant 124 to 247 d): of these 5 started a second lactation and entered the milking herd whereas 3 were culled. Data from heifers that had late EM or aborted during second gestation were excluded from the subsequent analysis. The mean calving to conception interval for heifers that conceived (without suffering from EM or abortion) was 130 ± 4.8 d, ranging from 42 to 488 d (n=338); the mean CI for these animals was 405 ± 4.8 d, ranging from 294 to 731 d (Table 2.5).

Table 2.5. Measures of primiparous fertility for 338 heifers which successfully conceived and calved (or are due to calve) for the second time

na Mean ± SEM RangeCommencement of luteal activity (CLA) (days) 170# 27 ± 1.1Days to 1st service (days) 337 80 ± 1.7 31-297

SID 5 (Rev. 3/06) Page 18 of 26

AFC / days

Freq

uenc

y / n

Days to conception (days) 338 130 ± 4.8 42-488Number services per conception (AI only) 309 2.3 ± 0.1 1-12Number services per conception (AI/Bull/ET)b 16 3.6 ± 0.6 1-10Pregnant to first servicec (%) 309 47% (138/309)Calving interval (CI) (days) 290 405 ± 4.8 294-731

# not all animals measured

GIRTH (as a proxy for weight) and HT before calving, and BCS and blood metabolite and hormone levels at wks 1 and 8 postpartum were considered as factors associated with primiparous fertility of all animals that were served after first calving. In addition, AFC, calving details (unassisted or assisted), calf status (dead or alive), and calf sex (male or female) at first calving, and the number of days to CLA were considered as factors associated with the fertility of primiparous heifers.

Calving assistance, and calf status and sex at first calving did not appear to influence the subsequent reproductive performance of animals. However for heifers that conceived and calved, several blood metabolite and hormone concentrations were associated with their fertility. Before calving, a high BHB concentration was associated with a prolonged interval to CLA, and increased the subsequent CI (P<0.05-0.01). Increased IGF-I concentration at wk 1 postpartum was associated with fewer days to CLA and to conception (P<0.05-0.01), and tended to be associated with fewer S/C and a shorter CI (P<0.1). Increasing urea and BHB concentrations at wk 1 postpartum was associated with an increased interval to CLA (P<0.1-0.05). At wk 8 postpartum, high urea concentrations were associated with a prolonged interval to CLA (P<0.05), whereas high glucose concentrations at this time tended to improve fertility with fewer days to first service and to conception (P<0.1).

When animals that conceived at <80 d after calving were compared to those conceiving >80 d postpartum, no differences were observed in the AFC (768 vs. 762 d) and days to CLA (26 vs. 27 d) between the two groups. However, animals that conceived at <80 d postpartum were served for the first time after calving on average 20 d earlier than heifers that conceived after 80 d (P<0.001). Animals conceiving within 80 d postpartum tended to have lower IGF-I and urea concentrations before calving (P<0.1) than those that conceived after 80 d postpartum.

Animals were grouped based on AFC into low (<700 d), medium (700-750 d), high (751-900 d) and late (>900 d). The CLA did not differ significantly between the groups, however the number of days to first service and conception, the number S/C and the CI was numerically highest for the heifers calving at a younger age.

Heifers that FTC during their first lactation calved for the first time at the same age (26.6 mo) as those heifers that did subsequently conceive (26.8 mo). Heifers FTC received on average 2.7 services (range 1 to 8). A number of differences in the metabolite and hormone concentration around first calving were observed between heifers FTC and those that conceived and calved for a second time (Fig. 2.3). With every 1 ng/ml increased in insulin concentration before calving, animals were 11 times more likely to FTC (OR=10.7, 95% CI 1.6 to 70, P<0.05). In contrast, animals with a high glucose concentration before calving were less likely to FTC (OR=0.1, 95% CI 0.01 to 0.7, P<0.05). In summary, most differences were apparent before calving with higher IGF-I, insulin, urea and BHB but lower glucose concentrations in FTC animals which was followed postpartum by a greater loss of BCS.

Figure 2.3. Changes in the mean (±SEM) plasma concentrations of (a) IGF-I, (b) insulin, (c) glucose, (d) urea and (e) BHB and (f) BCS of heifers FTC (n=39) and those that conceived after first calving (n=338).

(a) IGF-I (ng/ml) (b) Insulin (ng/ml) (c)Glucose(mmol/l)

0

20

40

60

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100

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-1 1 8

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(d) Urea (mmol/l) (e) BHB (mmol/l) (f) BCS

SID 5 (Rev. 3/06) Page 19 of 26

0

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2.2.7 Lactation dataFirst lactation records were available for 357 animals, of which 333 completed ≥150 DIM. Data from

incomplete lactations (<150 DIM) were considered separately. No information on second lactations is presented here as data are still being collected. The associations between the growth parameters and growth rate in each parameter during the rearing period and subsequent first lactation milk production are summarised in Table 2.6. Cows which were heavier at 6 mo, longer at 1 and 6 mo and had greater weight and HT increases from 1-6 mo all produced more total milk, although this was achieved through more DIM rather than more milk/d. As expected milk yield was also negatively related to BCS at 8 wks postpartum. Poorly growing animals between 1-6 mo therefore produced less milk even though they were older at calving.

The associations between the blood metabolites and hormones during the rearing period and around first calving and the subsequent first lactation milk production are summarised in Table 2.7. Juvenile insulin and glucose concentrations were related to subsequent milk output. In particular calves with higher insulin concentrations at 1 mo later produced more milk/d. Cows with higher BHB concentrations both just before and after first calving produced more milk in their first lactation. Low concentrations of IGF-I, insulin and glucose after calving were all associated with lower milk production per day, resulting in reduced 305 d yields.

Table 2.6. Multiple regression coefficient values for size parameters and growth rate during the rearing period significantly associated with first lactation milk production

Sample Variable DIM (d)

Total milk yield (kg)

Milk per day (kg/d)

305 d yield (kg)

Size parameters 1 mo CRL NS 50.4* NS NS6 mo WT 0.4* 13.4* NS NS

Girth 1.4* 37.8 NS NSCRL 1.7*** 40.9** NS NS

Pre-calving Girth NS 57.7* 0.15** NSPP wk 8 BCS -25.6* -1243.8*** -1.7* -666.3*

Growth rate 1–6 mo WT 87.1** 2534.2** NS NSCRL 240.4*** NS NS NSHT 396.2* 12053.3* NS NS

6-15 mo CRL -298.4** NS NS NS P-values; all <0.1, *<0.05, **<0.01, ***<0.001. NS = not significant.

Table 2.7. Multiple regression coefficient values for blood metabolite and hormones during the rearing period and around first calving significantly associated with first lactation milk production.

Sample Variable DIM (d)

Total milk yield (kg)

Milk per day (kg/d)

305 d yield (kg)

1 month Insulin -5.3 NS 0.86*** NS6 months IGF-I 0.4* NS NS NS

Glucose NS NS -1.8 -735.9Pre-calving BHB 84.6* 2305.4* NS 1429.7PP wk 1 IGF-I NS -13.1* -0.02 -11.1*

Insulin 45.8 NS -3.3 -1297.4Glucose NS NS -2.0* NSBHB NS 1136.8** 2.6** 527.0

PP wk 8 IGF-I NS NS -0.05** -8.9Insulin NS NS -4.6** NSGlucose NS -1676.7*** -5.0*** -1323.7***Urea 8.7* 396.9** 0.9** 305.3**

P-values; all <0.1, *<0.05, **<0.01, ***<0.001. NS = not significant.

2.2.8 Fertility in the second lactation

SID 5 (Rev. 3/06) Page 20 of 26

Animals were dried off approximately 2 mo (68 ± 3 d) before estimated second calving date. A total of 310 animals have to date calved for a second time, and 251 have been served at a mean of 74 ± 1.8 d after second calving. The mean number of days from calving to conception was 111 ± 4.4 d, with 45% (95/210) of animals conceiving to first service. To date, a total of 44 animals have been culled during their second lactation, with infertility the main reason for culling (25%).

3. Other work performed additional to the original objectivesAdditional opportunities arose during the course of the project to use the unique set of blood samples we have obtained to monitor diseases in UK herds:

3.1 In collaboration with Dr Janice Bridger (Royal Veterinary College), samples collected in our trial were used in a study to investigate the seroprevalence to bovine norovirus in the UK, as there was little previous information avialable. Diarrhoea in neonatal dairy and beef cattle is an important disease that causes considerable economic losses. Although the aetiological agents are numerous, two of the main viral pathogens are rotavirus (family Reoviridae) and noroviruses (family Caliciviridae). Newbury2 viruses had been detected in the cattle from the UK and have been suggested to be endemic in the cattle in the Netherlands. Jena virus had yet to be detected in cattle from the UK but 99% of German calves were seropositive. In our study, an ELISA was used to detect IgG to Newbury2 virus, Jena virus and rotavirus in sera and plasma from 3 groups of cattle: (i) 100 calves from the UK aged 6 months, (ii) 100 calves from Germany aged 6 months, (iii) 100 adult cattle from the UK, immediately following their first calving. All UK and German calves with a single exception (99.5%) and all adults (100%) were positive for rotavirus IgG. There was no difference between the UK and German calves regarding norovirus IgG seroprealence: 87% of UK and German calves contained IgG to Newbury2 virus, 77% of UK calves and 66% of German calves were seropositive for IgG to Jena virus. In the adult cattle, 99% were positive for IgG to Jena virus, 66% were positive for IgG to Nebwury2 virus. These results suggested that bovine noroviruses preferentially infect different age groups of cattle: calves appeared to be more susceptible to Newbury2 virus and adults to Jena virus. This study (Oliver et al. 2007) has highlighted the need for more research in this area, with the aim of eventually incorporating bovine noroviruses into the current scours vaccine.

3.2 In collaboration with Professor Joe Brownlie’s group at the Royal Veterinary College we have analysed 6 and 15 month samples for BVDV. All blood collected at 6 months of age has been tested for respiratory syncytial virus antibody, and analysis for Neospora caninum antibody is currently in progress. These data will be analysed with respect to the fertility, abortion and longevity data.

3.3. A SPARK award from Genesis-Faraday with Holstein UK (HUK) was awarded with the aim to characterise traits that increase longevity and robustness by linking information on fertility with linear trait assessment. A longer term goal was to identify phenotypic and genotypic characteristics of dairy youngstock which can predict their future performance and thus aid selection of the best animals for breeding at a young age. A total of 278 animals were classified by HUK across 15 farms (17 groups of heifers). We found that frame classification scores in first lactation were strongly related to several of the size measurements taken on heifers when juveniles, suggesting that measurements of skeletal size during the rearing period could assist in selecting the best heifers for breeding.

3.4 Merial have undertaken SNP analysis on the animals from this project under their Igenity programme to investigate possible links between genotypic markers and fertility traits. Blood samples from all the calves in Study 2 and 87 of the original cohort of cows in Study 1 which were still alive in March 2006 were sent to Orchid (Cellmark Diagnostics) in March 2006 for SNP analysis. Data have so far been obtained against a panel of 15 SNPs and this is currently being extended to encompass a larger panel. Pedigree data have been obtained back to the grandparents of animals on the study. Analysis to estimate heritability of the phenotypic traits measured and to link the SNPs to the phenotypic traits is still ongoing. A CASE studentship was awarded with Merial, starting in October 2007 to continue with this aspect of the work.

4. Knowledge Transfer

The results of this specific project have been published in 4 primary papers and 2 reviews so far and more are in progress (see Section 9).Note that it was not possible to publish more work at an earlier stage as the results of both studies depended on data collection on milk yield and survival which was not completed until the end of the project. In addition the work has been widely presented to a number of different audiences: scientific conferences, farmers groups and veterinary surgeons as listed in the main reference list. This work was jointly funded by

SID 5 (Rev. 3/06) Page 21 of 26

DairyCo and so the results are also being publicized by them e.g. at the Dairy Event and Livestock Show, Stoneleigh 2008.

5. References cited in project reportCoffey MP, Simm G, Hill WG, Brotherstone S (2003) Genetic evaluations of dairy bulls for daughter energy balance profiles

using linear type scores and body condition score analyzed using random regression. J Dairy Sci; 86:2205-12.Hansen M. Quantitative genetic analysis of mortality in Danish Holstein calves. 2004. PhD thesis. The Royal Veterinary and

Agricultural University, Denmark.Heinrichs AJ, Radostits OM. (2001) Health and production management of dairy calves and replacement heifers. In: Herd

health food animal production medicine, Radostits OM, WB Saunders Company, pp. 333-95.Hoffman (1997) Optimum body size of Holstein replacement heifers. J Anim Sci 75, 836-845.Oliver SL, Wood E, Asobayire E, Wathes DC, Brickell JS, Elschner M, Otto P, Lambden PR, Clarke IN and Bridger JC

(2007) Serotypes 1 and 2 bovine noroviruses are endemic in UK and German cattle. Journal of Clinical Microbiology Microbiology 45, 3050-3052.

Roy JHB. The Calf Fifth Edition: Volume 1 Management of Health. Butterworths. 1990Swali A and Wathes DC (2006) Influence of the dam and sire on size at birth and subsequent growth, milk production and

fertility in dairy heifers. Theriogenology 66, 1173-1184. Swali A and Wathes DC (2007) The influence of primiparity on size at birth, growth, the somatotrophic axis and fertility in

dairy heifers. Animal Reproduction Science 102, 122-136. Swali A, Cheng Z, Bourn N, Wathes DC (2008) Metabolic traits affecting growth rates of pre-pubertal calves and their

relationship with subsequent survival. Domest. Anim. Endocrinol. 35,300-313.Taylor VJ, Beever DE, Bryant MJ, Wathes DC (2003) Metabolic profiles and progesterone cycles in first lactation dairy

cows. Theriogenology 59:1661-77.Taylor VJ, Cheng Z, Pushpakumara PG, Beever DE, Wathes DC (2004) Relationships between the plasma concentrations of

insulin-like growth factor-I in dairy cows and their fertility and milk yield. Vet Rec; 155:583-8.

References to published material9. This section should be used to record links (hypertext links where possible) or references to other

published material generated by, or relating to this project.Publications

Full papersA. Swali and D.C. Wathes (2006) Influence of the dam and sire on size at birth and subsequent growth, milk production and fertility in dairy heifers. Theriogenology 66(5):1173-1184

A. Swali and D.C. Wathes (2007) The influence of primiparity on size at birth, growth, the somatotrophic axis and fertility in dairy heifers. Animal Reproduction Science 102(1-2):122-136

S.L. Oliver, E. Wood, E. Asobayire, D.C. Wathes, J.S. Brickell, M. Elschner, P. Otto, P.R. Lambden, I.N. Clarke and J.C. Bridger (2007) Serotypes 1 and 2 bovine noroviruses are endemic in UK and German cattle. Journal of Clinical Microbiology Microbiology 45(9):3050-3052

A Swali, Z Cheng, N Bourne, DC Wathes. (2008) Metabolic traits affecting growth rates of pre-pubertal calves, and their relationship with subsequent milk production, survival and a growth hormone receptor polymorphism. Domestic Animal Endocrinology. 35(3); 300-313 .

Papers submittedJ. S. Brickell, M. M. McGowan and D. C. Wathes. Aspects of Heifer Rearing. Cattle Practice. Submitted

J. S. Brickell, M. M. McGowan and D. C. Wathes. Management and metabolic influences on heifer growth rate during rearing on UK dairy farms. Domestic Animal Endocrinology. Submitted

J. S. Brickell, M. M. McGowan, D. U. Pfeiffer and D. C. Wathes. .Incidence and risk factors associated with the mortality of Holstein-Friesian heifers from birth to first calving on UK dairy farms. For submission to Animal (Oct 2008).

N. Bourne, A. Swali, S. Potterton, A.K. Jones and D.C. Wathes. The effect of age at first calving on future fertility and production in the dairy cow. For submission to Theriogenology Sept 2008.

SID 5 (Rev. 3/06) Page 22 of 26

Reviews (* specifically related to work undertaken in this project)IM Sheldon, DC Wathes & H Dobson (2006) The management of bovine reproduction in elite herds. Veterinary Journal 171(1):70-78

Wathes DC, Fenwick M, Cheng Z, Bourne N, Llewellyn S, Morris DG, Kenny D, Murphy J, Fitzpatrick R (2007) Influence of negative energy balance on cyclicity and fertility in the high producing dairy cow. Theriogenology 68 Suppl 1:S232-241

*DC Wathes, JS Brickell, N Bourne, A Swali and Z Cheng (2008) Factors influencing heifer survival and fertility on commercial dairy farms. Animal. 2(8): 1135-1143.

*DC Wathes (2008) Metabolic effects on the reproductive tract environment and conception rates in the dairy cow. Havemeyer Foundation Monograph Series No 21, p15-19.

RS Robinson, AJ Hammond, DC Wathes, MG Hunter and GE Mann (2008) Corpus luteum-endometrium-embryo interactions in the dairy cow; underlying mechanisms and clinical relevance. Reproduction in Domestic Animals. 43; Suppl2, 104-112

MA Velazquez, LJ Spicer, DC Wathes. The role of endocrine insulin-like growth factor-I (IGF-I) in female bovine reproduction. Domestic Animal Endocrinology, in press.

Published abstracts relating to this project

A Swali, VJ Taylor, DE Beever and DC Wathes (2004) Early development and subsequent metabolic parameters in Holstein-Friesian dairy cows. Endocrine Abstracts 8 P54. Presented Society for Endocrinology Meeting, Nov 2004, London.

A Swali and DC Wathes (2005) Do factors experienced during calf rearing affect subsequent fertility in Holstein-Friesian heifers? Reproduction in Domestic Animals 40, P118. Presented ESDAR: Sept 2005: Murcia, Spain.

JS Brickell, N Bourne, M McGowan and DC Wathes (2005) Mortality and growth rates of replacement dairy heifers on commercial farms. In Reproduction in Domestic Animals:40 (4). Editors W.K. Farstad, King W. A., Rodrigues, J. L. R, Suarez, S. S., Rath, D., Okuda, K., Martin, G., and Verstegen, J. p.343. Blackwell Publishing. Presented ESDAR: September 2005: Murcia, Spain.

N. Bourne, A. Swali, A.K. Jones, S. Potterton and D.C. Wathes (2007) The effects of size and age at first calving on subsequent fertility in dairy cows. In Reproduction in Domestic Ruminants VI. Ed JL Juengel, JF Murray and MF Smith. Nottingham University Press. Ruminant Reproduction Conference: August 2006: New Zealand.

JS Brickell, N Bourne, ECL Bleach and DC Wathes (2007) Influence of pre-weaning diet and sire on growth rates of replacement dairy heifers. In Reproduction in Domestic Ruminants VI. Editors J. L. Juengel, Murray, J. F., and Smith, M. F. p.493. Nottingham University Press. Ruminant Reproduction Conference: August 2006: New Zealand.

JS Brickell, N Bourne, Z Cheng and DC Wathes ( 2007) The incidence of calf mortality on dairy farms in southern England. Proceedings BSAS P107. Presented BSAS Annual Meeting: April 2007: Southport. Highly commended for President’s prize.

N Bourne, A Swali, AK Jones, S Potterton and DC Wathes ( 2007) Comparison of metabolic profiles and fertility in the same dairy cows during their first and second lactations. Proceedings BSAS O54. Presented BSAS Annual Meeting: April 2007: Southport.

JS Brickell, N Bourne, Z Cheng and DC Wathes (2007) Influence of plasma IGF-I concentrations and body weight at 6 months on age at first calving in dairy heifers on commercial farms. In Reproduction in Domestic Animals: 42 (supplement 2). Editors W. A. King, Martinez, E. A., McGowan, M., Rodrigues, J. L. R., and Sato, E. p.42. Blackwell Publishing. ESDAR: September 2007: Celle, Germany. Runner up in student competition.

JS Brickell, N Bourne and DC Wathes (2008) Relationships between blood metabolites and hormones before and after first calving in dairy heifers and their fertility during the first lactation. Proceedings BSAS 118. Presented BSAS Annual Meeting: April 2008: Scarborough.

JS Brickell, N Bourne, JD Nkrumah, N Otter and DC Wathes (2008) Bovine growth hormone receptor (BGHR) polymorphism – associations with metabolic, size and fertility traits in dairy heifers. Presented World Buiatrics Congress: July 2008: Budapest, Hungary.

Claire Wathes: Invited conference presentations

SID 5 (Rev. 3/06) Page 23 of 26

Awarded the RASE Research Medal 2006 for work on cattle fertility.

Relationships between production and reproduction (2005) The 26th European Holstein and Red Holstein Conference. Prague, Czech Republic.

Neonatal mortality and survival in the dairy herd – causes and consequences for lifetime productivity (2005) Genesis Faraday Workshop on “The genetics and genomics of pre- and neonatal survival”. Cambridge, UK.

IGF-I in the cow- relationships between yield, growth and fertility. Indian Society for the Study of Reproduction and fertility. Karnal, India. (February 2006)

Metabolic effects on the reproductive tract environment and conception rates. Havermeyer Workshop. Ravello, Italy. (May 2006).

3 seminars in New Zealand on cattle fertility in August 2007 to Dexcel, Massey University and Livestock Improvement Co.

Influence of negative energy balance on cyclicity and fertility in the high producing dairy cow. International Conference on Farm Animal Reproduction (ICFAR). 2007. Dolduc,

Factors influencing heifer survival and fertility on commercial dairy farms. BSAS Fertility in dairy cows: bridging the gaps. 2007 (Aug). Liverpool, UK.

Jessica Brickell: Invited conference presentations and workshops / courses

Aspects of Heifer Rearing (November 2008) BCVA. Killarney, Ireland

Genesis Faraday Annual Event: 2005. Poster Presented: Mortality and growth rates of replacement dairy heifers on commercial farms

Data on calf growth rates and mortality data were presented at a farmers meeting, hosted by Shepton Veterinary Centre, in March 2006.

CPD Course: March 2006: Royal Veterinary College. Exploiting genes by sire selection

DBR Course: July 2006: Liverpool University. Heifer Management

Genesis Faraday Annual Event: September 2006. Poster Presented: Influence of the sire and dam and pre-weaning diet on growth rates and IGF-I concentration of replacement dairy heifers

Genesis Faraday Annual Event: September 2007: Cambridge. Poster Presented: Improved breeding for longevity in dairy cows – links between fertility, milk production and conformation traits

Veterinary Practise Workshop for dairy farmers: November 2007. Heifer Management

Ruminators Meeting (dairy farmers society): March 2008. Heifer Management

DBR Course: June 2008: Liverpool University. Heifer Management

CPD Course: July 2008: Royal Veterinary College. Exploiting genes by sire selection

Veterinary Practise Workshop for dairy farmers: February 2009. Heifer Rearing

Other publications on cattle fertility published by the group during the period of this grant (2003-2008)

VJ Taylor, DE Beever, MJ Bryant and DC Wathes (2003) Metabolic profiles and progesterone cycles in first lactation dairy cows. Theriogenology 59: 1661-1677.

PGA Pushpakumara, NH Gardner, CK Reynolds, DE Beever and DC Wathes (2003) Relationships between transition period diet, metabolic parameters and fertility in lactating dairy cows. Theriogenology 60: 1165-1185.

N Bourne, DC Wathes, M McGowan and RA Laven (2003) Physiological response in dairy cattle supplemented with vitamin E above NRC requirements. Cattle Practice 11: 367-372.

VJ Taylor, DE Beever, MJ Bryant and DC Wathes (2004) First lactation ovarian function in dairy heifers in relation to pre-pubertal metabolic profiles. Journal of Endocrinology 180: 63-75.

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PM Dawuda, RJ Scaramuzzi, SB Drew, HJ Biggadike, RA Laven, R Allison, CF Collins and DC Wathes (2004) The effect of a diet containing excess quickly degradeable nitrogen (QDN) on reproductive and metabolic hormonal profiles of lactating dairy cows. Animal Reproduction Science 81: 195-208.

VJ Taylor, Z Cheng, PGA Pushpakumara, DE Beever and DC Wathes (2004) Fertility and yield in lactating dairy cows: relationship to plasma IGF-I in the peripartum period. Veterinary Record 155: 583-588.

VJ Taylor, DE Beever, MJ Bryant and DC Wathes (2006) Pre-pubertal measurements of the somatotrophic axis as predictors of milk production in Holstein-Friesian dairy cows. Domestic Animal Endocrinology 31:1-18.

RS Robinson, MD Fray, DC Wathes, GE Lamming and GE Mann (2006) In vivo expression of interferon tau mRNA by the embryonic trophoblast and uterine concentrations of interferon tau protein during early pregnancy in the cow. Molecular Reproduction and Development 73: 470-474.

J Patton, DA Kenny, JF Mee, FP O’Mara, DC Wathes, M Cook and JJ Murphy (2006) Effect of milking frequency and diet on milk production, energy balance and reproduction in dairy cows. Journal of Dairy Science 89:1478-1487.

RA Laven, RJ Scaramuzzi, DC Wathes, AR Peters and TJ Parkinson (2007) Recent research on the effects of excess dietary nitrogen on the fertility of dairy cows. Veterinary Record 160:359-362.

DC Wathes, Z Cheng, N Bourne, VJ Taylor, MP Coffey and S Brotherstone (2007) Differences between primiparous and multiparous dairy cows in the inter-relationships between metabolic traits, milk yield and body condition score in the periparturient period. Domestic Animal Endocrinology 33:203-225

N Bourne, R Laven, DC Wathes, T Martinez and M McGowan. (2007) A meta-analysis of the effects of Vitamin E supplementation on the incidence of retained foetal membranes in dairy cows. Theriogenology 67: 494-501.

S Llewellyn, R Fitzpatrick, DA Kenny, JJ Murphy, RJ Scaramuzzi and DC Wathes (2007) Effect of negative energy balance on the insulin-like growth factor (IGF) system in pre-recruitment ovarian follicles of postpartum dairy cows. Reproduction 133:627-639.

DC Wathes, N Bourne, Z Cheng, GE Mann, VJ Taylor and MP Coffey (2007) Multiple correlation analyses of metabolic and endocrine profiles with fertility in primiparous and multiparous cows. Journal of Dairy Science 90:1310-1325.

RA Laven, DC Wathes, KE Lawrence and RJ Scaramuzzi (2007) An analysis of the relationship between plasma urea and ammonia concentration in dairy cattle fed a consistent diet over a 100-day period. Journal of Dairy Research 74, 412-416.

MA Fenwick, R Fitzpatrick, DA Kenny, MG Diskin, J Patton, JJ Murphy and DC Wathes (2008) Interrelationships between negative energy balance (NEB) and IGF regulation in liver of lactating cows. Domestic Animal Endocrinology 34: 31-44.

MA Fenwick, S Llewellyn, R Fitzpatrick, DA Kenny, JJ Murphy, J Patton and DC Wathes (2008) Negative energy balance in dairy cows is associated with specific changes in IGF binding protein (IGFBP) expression in the oviduct. Reproduction 135 63-75.

N Bourne, DC Wathes, KE Lawrence, M McGowan and RA Laven (2008) The effect of parenteral supplementation of vitamin E with selenium on the health and productivity of dairy cattle in the UK. The Veterinary Journal 177, 381-387.

G M Haworth, W Tranter, J Chuck, Z Cheng and DC Wathes (2008) Relationships between age at first calving and first lactation milk yield and lifetime productivity and longevity in dairy cows. Veterinary Record 162, 643-647.

N Bourne, DC Wathes, M McGowan and R Laven (2008) A comparison between two routes of vitamin E supplementation on the vitamin E status of dairy cows at different stages of lactation. Livestock Production Science In press.

S Llewellyn, R Fitzpatrick, DA Kenny, J Patton and DC Wathes (2008) Endometrial expression of the insulin-like growth factor system during uterine involution in the postpartum dairy cow. Domestic Animal Endocrinology 34 391-402.

S Childs, CO Lynch, AA Hennessy, C Stanton, DC Wathes, JM Sreenan and DA Kenny (2008) Effect of dietary enrichment with either n-3 or n-6 fatty acids on systemic metabolite and hormone concentrations and on ovarian function in cattle. Animal. 2:6,883-893.

S Childs, AA Hennessy, JM Sreenan, DC Wathes, Z Cheng, C Stanton MG Diskin and DA Kenny (2008) Effect of level of dietary n-3 polyunsaturated fatty acid supplementation on systemic and tissue fatty acid concentrations and on selected reproductive variables in cattle. Theriogenology 70, 595-611.

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