Effects of pregnant mare serum gonadotrophin and prostaglandin F2 following a short-term progestagen treatment to induce oestrus and ovulation in ewes during the non-breeding and breeding season
1983
Fukui, Y. | Sotto, W.L. | Terawaki, Y. | Ono, H. (Obihiro Univ. of Agriculture and Veterinary Medicine, Obihiro (Japan). Meat Animal Reproduction Lab.)
All of the ewes of group A1 (10 ewes), B1 (13 ewes) and B2 (15 ewes), and 4 of the ewes of group A2 (10 ewes) showed oestrus within 5 days after treatment. Ovulation was observed in all 4 laparotomized ewes of group A1, B1 and B2 whereas no ovulation was observed in group A2. Non-return, pregnancy, lambing rates and number of lambs per ewe were: group A1; 80% (8/10), 40% (4/10), 30% (3/10) and 2.33, group A2; 75% (3/4), 10% (1/10), 10% (1/10) and 1.00, group B1; 69.2% (9/13), 69.2% (9/130 and 1.67 and group B2: 66.7% (10/15), 46.7% (7/15) and 1.43. In groups A1, B1 and B2, a peak of plasma oestradial - 17B was observed on the day before the incidence of oestrus and plasma progesterone levels increased, after ovulation. A similar oestradial-17B peak was observed in the ewes of group A2, but no ewe exhibited oestrus. Underlying reasons were disclosed. Treatment with MAP sponge + PMSG was effective while treatment with MAP sponge + PGF2 was ineffective for the induction of oestrus and ovulation during the anoestrus season. MAP sponge treatment combined with either PMSG or PGF2 was effective for synchronization of oestrus and ovulation during the breeding season, however, the former effects a closer synchronization.
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