Fodor István, Lang Zsolt, Ózsvári László
Department of Veterinary Forensics and Economics, University of Veterinary Medicine Budapest, Budapest, H-1078, Hungary.
Department of Biomathematics and Informatics, University of Veterinary Medicine Budapest, Budapest, H-1078, Hungary.
Asian-Australas J Anim Sci. 2020 Aug;33(8):1360-1368. doi: 10.5713/ajas.19.0474. Epub 2019 Dec 24.
The aim of our study was to determine the associations of heifer reproductive performance with survival up to the first calving, first-lactation milk yield, and the probability of being culled within 50 days after first calving.
Data from 33 large Holstein-Friesian commercial dairy herds were gathered from the official milk recording database in Hungary. The data of heifers first inseminated between January 1, 2011 and December 31, 2014 were analyzed retrospectively, using Cox proportional hazards models, competing risks models, multivariate linear and logistic mixed-effects models.
Heifers (n = 35,128) with younger age at conception were more likely to remain in the herd until calving, and each additional month in age at conception increased culling risk by 5.1%. Season of birth was related to first-lactation milk yield (MY1; n = 19,931), with cows born in autumn having the highest milk production (p<0.001). The highest MY1 was achieved by heifers that first calved between 22.00 and 25.99 months of age. Heifers that calved in autumn had the highest MY1, whereas calving in summer was related to the lowest milk production (p<0.001). The risk of culling within 50 days in milk in first lactation (n = 21,225) increased along with first calving age, e.g. heifers that first calved after 30 months of age were 5.52-times more likely to be culled compared to heifers that calved before 22 months of age (p<0.001). Calving difficulty was related to higher culling risk in early lactation (p<0.001). Heifers that required caesarean section were 24.01-times more likely to leave the herd within 50 days after first calving compared to heifers that needed no assistance (p<0.001).
Reproductive performance of replacement heifers is closely linked to longevity and milk production in dairy herds.
本研究旨在确定小母牛繁殖性能与首次产犊前的存活情况、首次泌乳产奶量以及首次产犊后50天内被淘汰概率之间的关联。
从匈牙利官方牛奶记录数据库收集了33个大型荷斯坦-弗里生商业奶牛场的数据。对2011年1月1日至2014年12月31日首次输精的小母牛数据进行回顾性分析，使用Cox比例风险模型、竞争风险模型、多元线性和逻辑混合效应模型。
受孕时年龄较小的小母牛（n = 35,128）更有可能留在牛群中直至产犊，受孕时年龄每增加一个月，淘汰风险增加5.1%。出生季节与首次泌乳产奶量（MY1；n = 19,931）有关，秋季出生的奶牛产奶量最高（p<0.001）。首次产犊年龄在22.00至25.99月龄之间的小母牛实现了最高的MY1。秋季产犊的小母牛MY1最高，而夏季产犊与最低产奶量有关（p<0.001）。首次泌乳50天内被淘汰的风险（n = 21,225）随着首次产犊年龄的增加而增加，例如，首次产犊年龄在30月龄之后的小母牛被淘汰的可能性是22月龄之前产犊小母牛的5.52倍（p<0.001）。产犊困难与泌乳早期较高的淘汰风险有关（p<0.001）。与无需助产的小母牛相比，需要剖腹产的小母牛在首次产犊后50天内离开牛群的可能性高24.01倍（p<0.001）。
后备小母牛的繁殖性能与奶牛群的寿命和产奶量密切相关。
