Cloprostenol for termination of pregnancy in cattle

Summary Two hundred and twenty seven dairy cows and heifers which had conceived at least 245 days previously were treated with dexamethasone alone (20 mg i/m), cloprostenol alone (500 µg s/c) or both drugs at different time-combinations in order to study the effect in terms of induction of parturition. Results showed that cloprostenol alone, or 8–11 days after dexamethasone, caused 81% and 96% of animals respectively to calve within 1–4 days of the cloprostenol treatment. Dexamethasone alone or injected on the same day as cloprostenol also advanced the day of calving but both spread and delay were longer than with the othertreatments. Animals treated with cloprostenol alone, or cloprostenol 8–11 days after dexamethasone, showed oestrous behaviour 24 hours before calving, though without adverse results. Calf survival was similar for all treated groups. Cloprostenol treatments were associated with a higher incidence of retained foetal membranes (28.2–5.7%) but also with a shorter interval from parturition to resumption of cyclicity.