Section of Animal Welfare and Disease Control, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, Copenhagen University, Frederiksberg, Denmark.
Section of Animal Welfare and Disease Control, Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, Copenhagen University, Frederiksberg, Denmark.
Prev Vet Med. 2019 Nov 1;171:104751. doi: 10.1016/j.prevetmed.2019.104751. Epub 2019 Aug 21.
Culling is an important management tool in dairy herds, as it affects herd economics and animal welfare. In relation to health, culling is usually studied as a consequence of health disorders, but it can also be regarded as a tool to manage health in the herd by making strategic culling decisions. In this study, we used data from the Danish Cattle Database in herd-wise survival analyses to investigate factors associated with culling, in relation to udder health, in 1,452 dairy herds. The data included milk yield, somatic cell counts (SCC), parity, and different disease related factors with a special focus on udder health. In each herd, observations and survival analyses were divided into five groups: mid lactation heifers, late lactation heifers, early lactation cows, mid lactation cows, and late lactation cows. The results showed that a high average milk yield reduced the culling hazard, and a number of risk factors (e.g., parity, a high SCC or treatment of mastitis) were associated with an increased hazard for culling. Importantly, the strength and direction of many of these associations was dependent on the lactation stage. The resulting coefficients were further analysed by principal component analysis and clustering to explore variations in culling risk factors amongst herds. In some herds, parity was an important factor for culling, while in other herds, average milk yield, SCC, or udder health were more important factors. However, clusters were substantially overlapping, indicating that the decision making process underlying culling is complex and multifactorial.
淘汰是奶牛场管理的重要工具，因为它会影响牛群的经济效益和动物福利。在健康方面，淘汰通常被视为健康障碍的结果进行研究，但也可以将其视为通过制定战略性淘汰决策来管理牛群健康的工具。在这项研究中，我们使用丹麦奶牛数据库中的数据，通过群体生存分析来调查与乳房健康相关的淘汰因素，该数据库包含了产奶量、体细胞计数（SCC）、胎次和与乳房健康相关的不同疾病因素，特别关注乳房健康。在每个牛群中，观察和生存分析分为五个组：泌乳中期的小母牛、泌乳后期的小母牛、泌乳早期的奶牛、泌乳中期的奶牛和泌乳后期的奶牛。结果表明，平均产奶量高会降低淘汰风险，而许多风险因素（例如胎次、高 SCC 或乳腺炎治疗）与淘汰风险增加有关。重要的是，这些关联的强度和方向在很大程度上取决于泌乳阶段。进一步通过主成分分析和聚类分析对淘汰风险因素进行了分析，以探索牛群之间淘汰风险因素的变化。在一些牛群中，胎次是淘汰的重要因素，而在其他牛群中，平均产奶量、SCC 或乳房健康是更重要的因素。然而，聚类结果存在很大重叠，表明淘汰决策背后的决策过程是复杂的，涉及多个因素。
