Ansari-Lari Maryam, Mohebbi-Fani Mehdi, Rowshan-Ghasrodashti Abbas
Department of Food Hygiene and Public Health, School of Veterinary Medicine, Shiraz University, Shiraz, Iran;
Department of Animal Health Management, School of Veterinary Medicine, Shiraz University, Shiraz, Iran;
Vet Res Forum. 2012 Fall;3(4):233-7.
This study was designed to investigate causes of culling in industrial dairy herds in Fars province and to describe the pattern of reason-specific culling with respect to age of animal and interval from calving to culling. A total number of 9 dairy herds were selected for the study and information about culling reasons, birth date, last calving date and culling date was collected for culled cows during 2005-2006. Infertility (32.6% of all culls) was the most prevalent reason of culling followed by mastitis (6.5%). The time interval from last calving to culling averaged 240 days (SD = 176) and nearly 28% of cows were culled in the first 100 days after calving. Mean age of animals at culling was 6 years (SD = 2.7) and median was 5.7 years. In Cox proportional hazard model for calving to culling interval, infertility (hazard ratio [HR] = 0.26) showed lower risk whereas mastitis (HR = 2.40), left displaced abomasum (HR = 2.60) and peripartum problems (HR = 2.60) had higher risk of culling compared with voluntary cull. In the Cox model for age at culling, risk of culling was significantly higher for infertility (HR = 1.70), left displaced abomasum (HR = 3.15), and peripartum problems (HR = 2.10) compared with voluntary culling. In conclusion, farmers tend to keep infertile cows for longer period from calving to culling while infertile cows are generally culled at younger age. Also, early culling appeared to have a high proportion of culls in the studied herds.
本研究旨在调查法尔斯省工业奶牛场的淘汰原因，并描述特定原因淘汰模式与动物年龄以及产犊至淘汰间隔的关系。共选择了9个奶牛场进行研究，并收集了2005 - 2006年期间淘汰母牛的淘汰原因、出生日期、最后产犊日期和淘汰日期等信息。不育（占所有淘汰牛的32.6%）是最主要的淘汰原因，其次是乳腺炎（6.5%）。从最后产犊到淘汰的时间间隔平均为240天（标准差 = 176），近28%的母牛在产犊后的前100天内被淘汰。淘汰时动物的平均年龄为6岁（标准差 = 2.7），中位数为5.7岁。在产犊至淘汰间隔的Cox比例风险模型中，与自愿淘汰相比，不育（风险比[HR] = 0.26）显示出较低的风险，而乳腺炎（HR = 2.40）、皱胃左移位（HR = 2.60）和围产期问题（HR = 2.60）有较高的淘汰风险。在淘汰年龄的Cox模型中，与自愿淘汰相比，不育（HR = 1.70）、皱胃左移位（HR = 3.15）和围产期问题（HR = 2.10）的淘汰风险显著更高。总之，从产犊到淘汰，农民倾向于让不育母牛饲养更长时间，而不育母牛通常在较年轻的时候被淘汰。此外，在所研究的牛群中，早期淘汰似乎占淘汰牛的比例较高。
