INDIVIDUAL ANIMAL AND MATERNAL RISK-FACTORS FOR MORBIDITY AND MORTALITY OF NEONATAL BEEF-CALVES IN COLORADO, USA

A prospective study was conducted to quantify the individual animal an d maternal factors that affected morbidity and mortality of calves in Colorado beef herds. The study subjects were all calves born in ten pa rticipating herds during the 1990 and 1991 calving seasons. All 3666 c alves born during the study period were individually identified at bir th, and subsequent disease events were recorded by the producers. The disease outcomes of interest and their observed incidence rates were: perinatal (birth to 12 h) mortality, 2.5%; general neonatal (12 h to 4 5 days) mortality, 2.2%; general neonatal morbidity, 4.4%; neonatal di arrhea, 1.1%; neonatal respiratory disease, 1.0%; mothering problems/w eak calves, 1.2%; and neonatal enterotoxemia/sudden death, 1.4%. Data analysis utilized multiple logistic regression. All analyses were adju sted for herd. Perinatal mortality was greater (P < 0.01) for calves e xperiencing dystocia and for twin calves. The incidence of general neo natal morbidity was also higher (P < 0.01) among calves born to diffic ult or twin births, and calves of 2-year-old dams (P = 0.06). General neonatal mortality was higher (P < 0.05) among twins and calves of 2-y ear-old dams. Difficult or twin birth, as well as 2-year-old dam were the most common risk factors associated with the more specific morbidi ty out-comes. No evidence of the dam's late-gestation level of nutriti on or seasonal effects on morbidity and mortality were observed.