Cow- and herd-level risk factors for on-farm mortality in Midwest US dairy herds.

摘要: The objectives of this study were to describe on-farm mortality and investigate cow- herd-level risk factors associated with in Midwest US dairy herds using lactation survival analysis. We analyzed a total approximately 5.9 million DHIA records from 10 states January 2006 December 2010. cow-level independent variables used the models first test-day milk yield, fat percent, protein fat-to-protein ratio, urea nitrogen, somatic cell score, previous dry period, calving interval, stillbirth, calf sex, twinning, difficulty, season calving, parity, breed. included herd size, 305-d mature-equivalent stillbirth percentage. Descriptive analysis showed that overall rate was 6.4 per 100 cow-years it increased 6.8 Mortality primary reason leaving (19.4% culls) followed by reproduction (14.6%), injuries other (14.0%), low production (12.3%), mastitis (10.5%). Risk factor hazard for higher ratio (>1.6 vs. 1 1.6), lower cows male calves, carrying multiple increasing longer difficulty breed (Holstein others). Decreased protein, shorter period. For factors, percentage stillbirths, interval. Cows yield had hazard. Results indicated records, especially those indicative negative energy balance cows, could be helpful identify animals at high mortality. Higher cow did not have association In addition, between management quality an important lowering mortality, thereby improving welfare.