Induced lactation in dairy ewes by various brief hormone treatments

Hormonal induction of lactation in 40 nonpregnant dairy ewes was attempted by daily injecting subcutaneously 25 mg estradiol-17 beta and 70 mg progesterone for 7 consecutive days. After an interval of 7 days the following treatments were applied: group I (10 ewes), nothing; group II, (10 ewes), 10 mg dexamethasone and 30 mg prednisolone; group III (10 ewes), 10 mg dexamethasone, 30 mg prednisolone, 400 IU insulin; and group IV (10 ewes), 10 mg dexamethasone, 30 mg prednisolone, 400 IU insulin, and 40 mg prostaglandin F2 alpha. Hand milking was initiated at day 16. Thereafter, ewes were milked twice daily for 60 days, and milk yields were recorded and sampled twice weekly for measuring fat, pH, acidity, specific gravity, total solids, lactose, and chloride content. Mean yield of milk of ewes in II was larger than of ewes in I and IV. Four ewes in I, 8 ewes in II, 5 ewes in III, and 3 ewes in IV out of 10 ewes in each group produced more than 200 ml milk daily. The peak milk yield of ewes in I was at day 43, in II at day 28, in III at day 7, and in IV at day 11 of the milking period. Injection of corticoids in the induction scheme of estrogen and progesterone resulted in greater lactogenic response and yields of milk, but injections of insulin or insulin and prostaglandin F2 alpha diminished these responses.