INFLUENCE OF NUTRITIONAL STATUS ON HORMONE-INDUCED SUPEROVULATION IN NORMALLY CYCLING EWES

Abstract

Two groups, each of 18 normally cycling ewes, were subjected to either a low plane (3.0 Mcal digestible energy) or a high plane (4.5 Mcal DE) of nutrition prior to and during breeding. All ewes were synchronized by means of progestagen-impregnated intravaginal pessaries, and one subgroup within each nutritional group received 800 IU PMS (pregnant mare serum) to induce superovulation. The average litter size was 1.78 and 0.89 for the low plane group, with and without PMS, respectively, and 2.10 and 1.44 for the high plane group, with and without PMS, respectively. The plane of nutrition significantly (P < 0.05) increased the lambing percentage, as did the PMS treatment (P < 0.01). There was no significant (P > 0.05) interaction between the plane of nutrition and PMS level. The results suggest that gonadotropin treatment combined with estrus synchronization could provide a commercially feasible means of increasing litter size in ewes.