Stevenson M A, Lean I J
Department of Animal Science, University of Sydney, Camden, New South Wales.
Aust Vet J. 1998 Jul;76(7):489-94. doi: 10.1111/j.1751-0813.1998.tb10190.x.
To identify risk factors for culling of dairy cows from eight New South Wales dairy herds.
A longitudinal population study of dairy cow culling in eight non-seasonally calving dairy herds in the Camden district of New South Wales. Cox's proportional hazards model was used to evaluate various risk factors for culling for a specific reason (sales, deaths, reproductive failure, disorders of the udder and low milk production).
Age at first calving was not a significant risk factor for culling. Milk production in the first lactation greater than the population mean did not influence length of productive life overall, but was associated with a greater hazard of removal for disorders of the udder. Risk of culling for reproductive failure differed significantly between farms, and was not related to events in the previous lactation such as calving-to-first service interval or calving-to-conception interval. Shorter calving intervals were associated with increased risk of removal for low milk production and disorders of the udder.
Longitudinal surveys to accurately identify reasons for removal from a wide range of herds, identification of herds with low culling rates (especially for reproductive failure and udder disorders), and the identification of practices associated with these culling rates would be worthwhile to the Australian dairy industry.
确定新南威尔士州8个奶牛群中奶牛被淘汰的风险因素。
对新南威尔士州卡姆登地区8个非季节性产犊奶牛群的奶牛淘汰情况进行纵向群体研究。采用Cox比例风险模型评估因特定原因（销售、死亡、繁殖失败、乳房疾病和低产奶量）而淘汰的各种风险因素。
头胎产犊年龄不是淘汰的显著风险因素。头胎产奶量高于群体平均水平对总体生产寿命长度没有影响，但与因乳房疾病而被淘汰的风险增加有关。不同农场因繁殖失败而被淘汰的风险差异显著，且与前一胎的事件（如产犊至首次配种间隔或产犊至受孕间隔）无关。较短的产犊间隔与因低产奶量和乳房疾病而被淘汰的风险增加有关。
进行纵向调查以准确确定从广泛牛群中淘汰的原因，识别淘汰率低的牛群（特别是因繁殖失败和乳房疾病），以及识别与这些淘汰率相关的做法，对澳大利亚奶牛业将是有价值的。
