Genetic Relationship Between the United States and Canadian Holstein Bull Populations

The average additive genetic relationship and degree of connectedness between American and Canadian Holstein AI bull populations were estimated. This project was undertaken to determine the feasibility of a joint United States-Canadian sire evaluation to estimate genetic base differences between the two countries‘Holstein bull populations. Data were provided by USDA and Agriculture Canada for bulls evaluated in each country. Bulls were designated as American, Canadian, or dual national origin based on their country of registration and national origin of their parents. A total of 13,079 American, 1683 Canadian, and 256 dual origin bulls were included in the inverse relationship matrix. When both sire and maternal grandsire relationships were included in the matrix, there were 174 disconnected groups; however, 99% of the American bulls and 97% of the Canadian bulls were in a single group. The average aij between the American and Canadian population was 4.6×10−5. Despite the low average additive relationship between the two national populations, the high degree of connectedness in the inverse relationship matrix, when using both sire and maternal grandsire relationships, suggests sufficient genetic ties between the two populations to conduct a meaningful joint sire evaluation

Need for protein supplementation in the diet of growing dairy bulls fed total mixed ration based on moderate digestible grass silage and barley

The objective of the present experiment was to study the need for the protein supplementation in the diet of growing dairy bulls (initial live weight 272 ± 28.5 kg and final live weight 666 ± 31.2 kg, on average) fed total mixed ration based on moderate digestible grass silage and barley. The experiment comprised 24 Finnish Ayrshire bulls and 8 Holstein-Friesian bulls and included four treatments. The control diet (C) consisted of moderate digestible (653 g digestible organic matter in dry matter (DM) grass silage (450 g kg-1 DM), barley grain (275) and barley fibre (275) without protein supplementation. Three isonitrogenous experimental diets included also extra protein, i.e. (1) rapeseed meal (RSM) (supplementation 530 g DM per animal day-1), (2) wet distillers’ solubles (WDS) (600 g) and (3) a mixture of barley protein (90% of fresh weight) and wet distillers’ solubles (10) (BPWDS) (480 g). In all isonitrogenous diets the crude protein content of concentrate increased from 137 to 150 g kg-1 DM (9%) compared with the C diet. All bulls were fed total mixed ration ad libitum. The energy content of all diets was 11.6 MJ kg-1 DM. The live weight gain of the bulls tended to be higher with the BPWDS diet than with the C diet (C 1214 vs. BPWDS 1301 g d-1; p = 0.10), but the treatments had no significant effect on carcass gain, feed conversion or slaughter parameters. Only the BPWDS diet differed significantly from the C diet in DM (C 9.69 vs. BPWDS 10.38 kg DM d-1; p < 0.01) and energy intake (C 112.4 vs. BPWDS 120.3 MJ d-1; p < 0.05). The apparent organic matter digestibility (OMD) was 5% higher in the BPWDS diet than in the C diet (p < 0.001), but the RSM and WDS diets did not differ from the C diet in OMD. The results indicate that the supply of protein in dairy bulls is most probably adequate with moderate digestible, well-preserved grass silage and barley-based concentrates when intake of digestible organic matter is high enough to support microbial protein synthesis in the rumen

Prevalence of BoHV-1 seropositive and BVD virus positive bulls on Irish dairy farms and associations between bull purchase and herd status

peer-reviewedBackground BVD and IBR are contagious viral diseases highly prevalent in Irish cattle. Despite their significant reproductive and economic impact very little is known about the BVD and IBR status of stock bulls (a bull used for breeding purposes). There are still a high proportion of dairy farms in Ireland that rely on the use of a bull for breeding cattle and ensuring the fertility of the bulls is of paramount importance for the efficiency of the farms. The prevalence of BoHV-1 and BVD in stock bulls in Irish dairy herds has never been investigated. The objectives of this study therefore were: (i) to provide descriptive, observational data on the use of stock bulls on Irish dairy farms; (ii) to investigate the BVD and BoHV1 status of a sub-set of stock bulls; (iii) to investigate factors associated with BVD and BoHV1 status of stock bulls and (iv) to investigate factors associated with dairy herd status for BVD and BoHV1, including any associations with the use of stock bull. A total of 529 blood samples from bulls involved in the dairy breeding process were analysed for BVD virus using RT-PCR, and BoHV-1 antibodies by ELISA test. A total of 305 different dairy herds took part in the study and the overall BVD and BoHV-1 herd status was determined by ELISA using four bulk tank milk samples over the 2009 lactation. Logistic regression was used to investigate the associations between the stock bulls and BVD and BoHV-1 herd and individual status. Results Of the 305 total participating farms, 235 farms (77 %) had at least one bull and 167 farms had purchased bulls. Two bulls (0.4 %) out of 529 tested were found positive for BVD virus and 87 (16.7 %) tested seropositive for BoHV-1. Some significant associations were identified between the purchase of bulls and both viral diseases. Purchased bulls were three times more likely to be seropositive for BoHV-1 than homebred bulls. In the same way, herds with purchased bulls were three times more likely to be classified as seropositive for BVD and four times more likely to have evidence of recent BoHV-1 circulation than farms where all the bulls were homebred. Conclusions The prevalence of BoHV-1 and BVD in stock bulls in Irish dairy herds has never been investigated. This study highlights the widespread use of stock bulls in Irish dairy herds, as well as the high rate of exchange of bulls between farms. Significant associations were found between the origin of the bull and their serological BoHV-1 status. In keeping with these results, bulls with higher number movements between farms were more likely to be seropositive for BoHV-1

Investigations into variation in growth performance of cattle at pasture : a thesis submitted in partial fulfillment of the requirements for the Masters in Applied Science (Animal Science) at Massey University

The aim of this experiment was to examine relationships between the growth rate (LWG) and estimates of voluntary feed intake, feed conversion efficiency (GFE), temperament, susceptibility to chronic (longer-term) stress, indices of mature weight and indices of metabolic rate within groups of similar cattle run together. Sixty Hereford x Angus cross 9 month old male cattle (30 bulls and 30 steers) were allocated to either the fastest growing two-thirds or slowest growing third (Restricted-Slow Group (RS)), based on their growth rate over a 100 day period commencing on d0. The fastest growing two-thirds were randomly allocated between the Fast (F) and Restricted-Fast (RF) groups. Restriction of growth of the RF and RS treatment groups commenced on d112. Treatment group F cattle (10 bulls, 10 steers) were grown rapidly to achieve slaughter weights of 550 and 525kg for bulls and steers at 16-18 months of age, respectively. Treatment group RS and RF were fed to achieve a similar weight at about 25 months of age. The trial was therefore a 3 x 2 factorial with 3 growth path groups and 2 castration groups. Bulls gained 18% faster than steers in the F treatment group up to slaughter (1.10±0.03 and 0.93±0.03kg/d, respectively, P<0.001). No significant difference was found between live weight gains of bulls and steers of the RF and RS groups(0.56±0.02 vs. 0.51±0.02kg/d, respectively, NS). Organic matter intakes (OMI) measured using chromium intraruminal capsules ranged between 1.45-170,1.19-1.53, 0.89-1.02 and 0.94-1.20kg OMI/100kg LWT/d for the four separate intake periods. These values were all lower than predicted values, reflecting possible poor pasture quality and/or inaccurate measurement of OMI. During the d90-100 period under ad libitum feeding the bulls were significantly more efficient than the steers (0.24±0.01 vs. 0.18±0.01kg LWG/kg OMI,P<0.001), and F and RF cattle had significantly higher feed conversion efficiency (GFE) than RS cattle (0.23±0.0l vs. 0.16±0.02 kg LWG/kg OMI, P<0.005). During the later intake periods the fast-growing F treatment group was significantly more efficient at food conversion than the restricted groups (RF and RS) on all occasions. No differences in temperament, as assessed by stepping rate and subjective scoring in a weigh crate, and flight distance measures, were found between bulls and steers. The RF treatment group had a consistently lower, but not always significantly different, temperament scores than the F or RS groups. Plasma cortisol levels were significantly (P<0.001) lower in bulls than in steers on all occasions. No sex differences existed in muscle glycogen content. Weight-adjusted withers heights was lower (P<0.05) in bulls than in steers on d208, 306 and 579, however there was no differences between the treatment groups. At slaughter the treatment F cattle had shorter carcass lengths, lighter livers, greater fat depths and kidney fat weights (P<0.001) than the RF and RS groups. Bulls had shorter femur bones, lower fat depth and kidney fat weight and liver weights, than steers (P<0.005) of the same carcass weight. Relationships were evaluated across all 60 cattle together by expressing each trait as a residual for each animal relative to the mean for its sex by treatment group. Measures of average daily gain, OMI, GFE and muscle glycogen levels were not very repeatable over time as measured by correlation coefficients. Temperament indices (range 0.31-0.71, P<0.05) and cortisol levels (range 0.29-0.48, P<0.05) were repeatable over time. Weight-adjusted height measurements (range 0.36-0.48, P<0.01) were also repeatable when all 60 cattle were measured. Relationships were investigated between various measurements and LWG prior to the measurement, LWG to 16 months of age and LWG to slaughter. No significant consistent relationships were observed between various long-term growth rates and either GFE, temperament, indices of-mature weight or -chronic stress. Moderate but inconsistent relationships were found between OMI and longer-term gain. It appears from this study that no consistent relationships between the various measurements and longer-term LWG exist in the cattle studied

Effects of replacing different proportions of barley grain by barley fibre on performance of dairy bulls

The objective of the present experiment was to study the effects of partial replacement of barley grain with barley fibre (BF) on animal performance, carcass traits and diet digestibility of growing dairy bulls. The feeding experiment comprised 20 Finnish Ayrshire bulls and 12 Holstein-Friesian bulls, and four treatments (8 bulls per treatment). There were four diets with two offered at stage 1 (from the initiation of the study to 450 kg live weight) and four at stage 2 (from 450 kg live weight to slaughter). The control diet (BF0) included grass silage (460 g kg–1 dry matter) and barley grain (540), BF25 diet included grass silage (460), barley grain (405) and BF (135), BF50 diet included grass silage (460), barley grain (270) and BF (270), and BF75 diet included grass silage (460), barley grain (135) and BF (405). At stage 1 there were only two treatments (BF0 and BF50) and at stage 2, all four treatments were included. All bulls were fed total mixed ration ad libitum. The mean initial live weight of the bulls was 261 kg and the mean final live weight 650 kg. At stage 1 there were no significant treatment differences in dry matter, energy or protein intakes or in live weight gain. At stage 2, replacing barley grain with BF led to a linear decrease of daily live weight gain (P < 0.05) and a linearly reduced feed conversion (kg dry matter kg–1 live weight gain) (P < 0.05). The apparent digestibility of the organic matter and neutral detergent fibre decreased linearly with increasing BF supplementation (P < 0.001). The dressing proportion and the carcass fat score decreased linearly (P < 0.05) with partial replacement of barley grain with BF. On carcass conformation, treatment had a significant (P < 0.05) quadratic effect: the BF25 and BF50 diets were classified highest. The results indicate that 50% of barley starch can be replaced with BF without affecting growth, but feed efficiency factors may decrease when barley starch is replaced with BF. At 75% replacement, feed intake was reduced, which resulted in a lower energy intake and reduced level of performance

Physiological and behavioural aspects of housing stress in cattle

End of project reportThe effect of various space allowances on pituitary, adrenal, immune responses and performance was investigated in 72 Holstein x Friesian bulls. Bulls (403 ± 3.5 kg) were blocked by weight and randomly assigned into two groups (familiar, F and unfamiliar, UF) x three (1.2, 2.7 and 4.2 m2 per bull; n = 24 bulls per space allowance) treatments and housed for 83 days in 18 pens (n = 4 per pen). Blood samples were collected on day –1, 0, 3, 14, 36 and 77 with respect to mixing and housing on day 0. The bulls were administered with adrenocorticotrophic hormone (ACTH) on day 3 and corticotrophin-releasing hormone (CRH) on days 14, 36 and 77. The basal cortisol concentrations were not affected (P>0.05) by mixing of familiar and unfamiliar bulls. On day 3, basal cortisol was greater (P0.05) of treatment and treatment x time on ACTH. On day 14, interferon-? production was lower (P0.05) different for those housed at 1.2 m2. Bulls housed at either space allowances had (P<0.05) neutrophilia, lymphopenia, eosinopenia and decreased haemoglobin on day 3 compared with day 0. The liveweight gain from days 0 to 83 was lower (P< 0.05) in bulls housed at 1.2 compared with those at 2.7 and 4.2 m2. Housing bulls at 1.2 m2 space allowance had a detrimental effect on their growth and was associated with an acute rise in plasma cortisol concentration (on day 3) compared with space allowances of 2.7 and 4.2 m2/bull.European Union Structural Funds (EAGGF

Evaluation of the Progeny of Beef Sires Differing in Genetic Merit

End of project reportThe Irish Cattle Breeding Federation (ICBF) publishes breeding values (BVs) for beef bulls. Historically, BVs were expressed in index form relative to the base population. Sometime ago this changed to expression in units of measurement of trait. This change occurred in the course of this project and was accompanied by some re-ranking of bulls. BVs are published for growth, carcass grades and calving traits. Growth BV is expressed as carcass weight but there is no indication if this results from higher live weight gain or from a higher kill-out proportion and there is no indication of any consequences for feed intake or efficiency. • The objectives of the project were (i) to compare progeny of bulls of high and low growth genetic index, for growth, feed intake, slaughter traits and carcass traits, (ii) to partition the extra live weight of progeny of high growth index bulls into carcass and non-carcass parts, and (iii) to partition any extra carcass weight of progeny from high growth index bulls into its component fat, muscle and bone fractionsEuropean Unio