CALVING EFFECTS ON FRENCH BEEF-COW FERTILITY

Infertility of nursing cows was studied by means of a survey carried out on 116 French herds and 3583 nursing cows (mostly Charolais breed). The relationship between calving problems and infertility (non-pregnant cow or calving interval over 1 year) was adjusted for parity, length of time between calving and turnout, calving complications, cleanliness, housing and geographical area, using a multiple logistic model with random effect. Infertility risk increased with the level of calving assistance; this effect was particularly high when there was a hard assistance (odds ratio of 1.5) or a caesarean section (odds ratio of 6). Moreover, the effect of calving problems on infertility was due, to a small degree only, to placental retention and subsequent puerperal endometritis.