DESCRIPTION OF COW CALF PRODUCTIVITY IN NORTHWESTERN QUEBEC AND PATH MODELS FOR CALF MORTALITY AND GROWTH

A random sample of 651 assumed-pregnant cows was drawn from 26 randoml y selected beef herds in Northwestern Quebec, Canada. The cows were fo llowed with their calves (n=568) for one production period. Data were collected on calving conditions, calf mortalities, and the presence of diarrhea and pneumonia in calves during the first 2 weeks of life, Th e calves were weighed and measured for withers height, at 3-4 weeks of age and at the weaning (median of 203 days of age). Cow-calf producti vity was described and two path models were built, one for calf mortal ities and the other for calf growth. The percentage of weaned calves w as 78.8%, the risk of perinatal mortality, within 24 h of birth, 4.4%, and the risk of neonatal mortality, from 24 h to 30 days of age, 7.7% , were estimated. The mean 200 day weight (adjusted for sire breed) wa s 217 kg for female calves and 232 kg for male calves. Birth with assi stance and birth between December and March (versus in April or May) w ere associated with an increased risk of dying during the perinatal pe riod; birth in a maternity pen was associated with a decreased risk of perinatal mortality. The presence of diarrhea or pneumonia during the first 2 weeks of life was associated with an increased risk of dying between 24 h and 30 days of age and with a decreased achieved growth a t 30 days without a subsequent full compensatory gain at the weaning.