Risk factors for culling and deaths in eight dairy herds

摘要

Eight non-seasonally calving dairy herds were examined in the Camden district of New South Wales, Australia, between 1 September 1992 and 31 August 1994. 527 cows were culled from the farms during the study and 902 were present at the end. 212 cowswere transferred to new herds. 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 ofculling 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.