Induced parturition with corticosteroids: a comparison of four treatments

Summary

A field trial was conducted to compare four injection regimes of corticosteroids to induce parturition. The treatments were: I 20–25 mg intramuscular injection of dexamethasone trimethyl acetate; II 20 mg dexamethasone trimethyl acetate initially, repeated 6 days later; III 20–25 mg dexamethasone trimethyl acetate followed 8 days later by a 20 mg injection of betamethasone: IV betamethasone daily starting at 1 mg/day and doubling every second day until day 9 beyond which a 16 mg/day level was maintained until calving. Data were collected from 879 cows on 46 farms. Calf mortality, considering only cows treated at least ten days before calving, was 19%, II 16%, III 5% and IV 9% for the four treatments and increased with increasing prematurity. Response time (initial injection to calving) was 11.5, 10.3, 10.0 and 9.2 days for the four treatments and increased by 0.7 days for each week increase in prematurity at first injection. Mean prematurity at birth was 15 days. Sixteen percent of cows had retained foetal membranes 24 hours after calving. Of 447 cows with fertility data, 90 were culled non-pregnant and 68 had calving induced again the season following the trial. Mean time from calving to conception for those calving normally was 57.2 ± 17.4 days. Prematurity and retained foetal membranes did not affect the calving — conception interval.