Early induction of parturition and initiation of lactation in sheep

Dexamethasone and estradiol benzoate were used to induce parturition in ewes at about day 120 of gestation as part of a program to reduce the time taken to progeny-test carpet-wool rams by evaluating the birthcoats of their offspring. Ten ewes received 5 injections of 12 mg dexamethasone over 2.5 days commencing on day 117. Eight lambed 3.1 +/- 0.53 days after the final injection. Of 14 ewes which received 20 mg estradiol benzoate on day 118, three delivered lambs, 2.0 +/- 0.41 days after injection. All lambs were born dead or died within 2 hours of birth. Following parturition all ewes came into lactation. The dexamethasone group produced more colostrum, with higher total solids content than the estradiol group. However, the volume was less than in a control group which lambed at full term. It was concluded that dexamethasone could be used successfully to induce parturition at 120 days and that onset of lactation was similar to that which occurs at full term.