Induction of parturition in cattle during the later stages of pregnancy: a comparison of three treatments.

To overcome dystocia, commonly associated with fetal oversize in prolonged pregnancies, parturition was induced with one of three agents: betamethasone, cloprostenol or dinoprost. Cows were treated on day 280 of pregnancy or later, and the average (+/- sd) gestation length was 287 days (+/- 5.1). Of the 75 cows treated, only one did not respond by calving within 72 hours of treatment. The time from treatment to calving was the same for all treatments; approximately 42 hours. Four animals required veterinary assistance at calving and three others required farmer assistance. No further assistance was essential. Four days after birth three calves had died. The dams were three heifers which required veterinary assistance at calving. The incidence of retention of fetal membranes was similar after the three agents, approximately 38 per cent. Those cows which retained the fetal membranes took significantly longer to respond to treatment than those which did not. Irrespective of placental retention, there was no difference among treatments in the subsequent calving to conception interval; an overall mean value of 84 days was recorded.