Reduced incidence of retained placenta with induction of parturition in the cow.

Two experiments were designed to determine whether pretreatment with Opticortenol (OPT), a long-acting corticosteroid, prior to induction of parturition with 25 mg of dexamethasone (DEX) alone or in combination with 500 mug cloprostenol (CLO) would result in a reduced incidence of retained placenta. In Experiment 1, 70% of the cows pretreated with 25 mg OPT on Day 270 of gestation calved before or within 24 hours of the scheduled induction treatment on Day 277. Cows induced to calve with DEX plus CLO without OPT pretreatment had an increased rate of placental retention (P<0.05), whereas, cows that received OPT were not different from the controls. In Experiment 2, cows received either 1 mg/25 kg OPT (high dosage) or 1 mg/50 kg OPT (low dosage) on Day 270 of gestation and were induced with DEX plus CLO on either Day 274 (4 days) or Day 276 (6 days). Cows claved 29.0 to 31.8 hours after induction treatment with 95% beginning to calve between 0700 and 1900 hours. The interval from calving to placental release and the incidence of retained placenta was not different between the high dosage 6-day group (29.4+/-8.2 hours, 29%) and the non-induced control cows (16.1+/-10.7 hours, 5%). When three cows in the high dosage 6-day group that retained their placentas for 30 to 36 hours were considered as not retained, the incidence of placental retention for that group was reduced still further to 17%. First service conception rates and pregnancy rates were lower in cows with retained placentas. Differences were significant (P<0.01) in Experiment 1 but not in Experiment 2. It was concluded that pretreatment with 1 mg/25 kg OPT 6 days prior to induction of parturition with DEX plus CLO in combination results in a predictable calving time, high calf viability, and a low incidence of placental retention.