Department of Reproduction, Obstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium.
Department of Reproduction, Obstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium.
Prev Vet Med. 2021 Aug;193:105392. doi: 10.1016/j.prevetmed.2021.105392. Epub 2021 May 26.
Longevity is an important trait both from an economic and social perspective. Modern dairy cows are criticized for their short productive lifespan: only a minority of animals survives to a fourth lactation, implying that most cows are culled before reaching their maximal potential. In contrast, the population of 100 t cows (HT), reaching the threshold of 100,000 kg lifetime milk yield, is growing rapidly. As these cows combine a long lifespan with high functionality, a better understanding of their intrinsic characteristics might help us to improve the overall lifespan and lifetime production in dairy cows. The aim of the present research was to compare HT with their less-producing herd mates in order to identify intrinsic cow factors associated with longevity and high lifetime production. Therefore, we matched 26,248 HT with 691,597 herd mates, born in the same year in the same herd. Data were provided by Coöperatie rundveeverbetering (CRV) and contained birth dates, calving dates, milk yield and dam information. In addition, scores for conformation traits based on classifications in the first lactation and breeding values (for milk yield, fertility, udder health and claw health) were provided. Multivariable conditional logistic regression models were built to identify factors associated with reaching a lifetime milk yield of 100,000 kg. Results revealed cows born in September and born out of heifers to have the highest odds to become a HT. When cows received a score ≥ 83 (population average 80) for udder and feet & legs conformation, they had higher odds of reaching the 100,000 kg threshold. While a greater body condition and larger rump angle increased the odds of becoming a HT, this was decreased in cows with a large body depth. Finally, breeding values for milk yield, fertility, udder health and claw health were positively associated with the likelihood of reaching a lifetime milk yield of 100,000 kg. In conclusion, to increase lifetime milk yield in dairy herds, farmers should select heifers with high scores for conformation traits like udder and feet & legs and high breeding values for milk yield, fertility and udder health. Furthermore, our data suggest that being born in September out of a heifer potentially contributes to reaching a high lifetime milk yield.
长寿是一个具有重要经济和社会意义的特征。现代奶牛因生产寿命短而受到批评：只有少数动物能存活到第四次泌乳期，这意味着大多数奶牛在达到最大潜力之前就被淘汰了。相比之下，100 吨奶牛（HT）的数量正在迅速增长，达到了 10 万公斤终生产奶量的门槛。由于这些奶牛具有长寿命和高功能，因此更好地了解它们的内在特征可能有助于我们提高奶牛的整体寿命和终生生产力。本研究的目的是将 HT 与生产性能较低的同群奶牛进行比较，以确定与长寿和高终生生产相关的内在奶牛因素。因此，我们将 26248 头 HT 与同一年在同一家畜群中出生的 691597 头同群奶牛进行了匹配。数据由 Coöperatie rundveeverbetering（CRV）提供，包含出生日期、产犊日期、产奶量和母本信息。此外，还提供了基于第一泌乳期分类的体型特征评分和产奶量、繁殖力、乳房健康和蹄腿健康的育种值。建立多变量条件逻辑回归模型来确定与达到 10 万公斤终生产奶量相关的因素。结果表明，9 月出生和从后备牛中出生的奶牛成为 HT 的几率最高。当奶牛的乳房和蹄腿体型特征评分≥83 分（群体平均 80 分）时，它们达到 10 万公斤产奶量的几率更高。虽然更大的体况和更大的臀部角度增加了成为 HT 的几率，但在体躯深度较大的奶牛中，这种几率会降低。最后，产奶量、繁殖力、乳房健康和蹄腿健康的育种值与达到 10 万公斤终生产奶量的可能性呈正相关。总之，为了提高奶牛群的终生产奶量，农民应该选择乳房和蹄腿体型特征评分高、产奶量、繁殖力和乳房健康育种值高的后备牛。此外，我们的数据表明，9 月从后备牛中出生可能有助于达到高终生产奶量。
