Risk factors for high herd level calf morbidity risk from birth to weaning in beef herds in the USA

We analyzed data from a national survey of beef cow-calf producers in the USA to quantify the effects of hypothesized risk factors on herd-level calf morbidity risk from birth to weaning. The analysis included 2490 herds from 23 states. Two stepwise logistic regressions were fit to identify factors associated with greater than or equal to 10% morbidity. The first model included all herds dichotomized into high-morbidity herds with greater than or equal to 10% morbidity and low-morbidity herds with <10% morbidity. The second model excluded herds with between 5 and 10% morbidity, and compared greater than or equal to 10% morbidity with less than or equal to 5% morbidity. The risk of dystocia was categorized into five levels for analysis; all non-zero categories were associated with increased odds of being a high-morbidity herd compared to herds with no dystocia (OR=2.7-5.5). Having >70% of cows and heifers calves in confinement also increased the odds of being a high-morbidity herd (OR=1.8). The population attributable fractions for dystocia and confined calving for the model including all herds dichotomized at 10% morbidity were 0.41 and 0.11, respectively. The summary population attributable fraction for both factors was 0.46. (C) 2000 Elsevier Science B.V. All rights reserved.