RISK-FACTORS FOR POSTPARTUM ANESTRUS IN CHAROLAIS BEEF-COWS IN FRANCE

Data from 248 Charolais cows from 20 herds of the Puisaye region (Yonn e, France) were collected during winter 1991-1992 to investigate risk factors affecting post-partum anoestrus. Blood was collected 60 days a fter calving; diagnosis of cyclicity was established by progesterone r adioimmunoassay. Herd variables were housing type, lighting of herd ac commodation, use of nutritional flushing and nutritional variables (pr otein and energy before and after calving), and individual variables w ere parity, ease of calving, body-condition score and body weight at c alving and at Day 60, exposure to bulls and calving period. Sixty days post-partum, 62.1% of cows were cyclic. Logistic regression was used to calculate odds ratio (OR). A random effects model was used to take into account the two levels of variables (animal and herd). Although i t was defined subjectively, lighting was the only significant herd-lev el risk factor. Odds of anoestrus were higher in dark than in light ac commodation (OR=6.2, CI 1.2-33.3). Primiparous cows had a higher anoes trus risk than multiparous cows (OR=10.2, CI 2.9-36.5). Compared with light cows, heavy or medium weight cows at calving had a lower anoestr us risk (OR=0.25, CI 0.07-0.91, and OR=0.20, CI 0.07-0.61, respectivel y).