Gonadotrophin stimulation of ewes that are not pregnant following multiple matings during the season

Abstract

In this study, the aim was to obtain pregnancy following synchronization and to increase profitability in ewes that did not become pregnant during the breeding season after at least 3 matings. Nonpregnant Middle Anatolian Merino ewes (n = 117) were given a progesterone sponge for 9 days. At the time of sponge removal, the ewes received 250 IU pregnant mare serum gonadotropin (PMSG) + 125 µg prostaglandin F2α (PGF2α). Two days later, they were injected with either human chorionic gonadotropin (hCG) (Group I, n = 48) or gonadotropin-releasing hormone (GnRH) (Group II, n = 43), or remained as a control (Group III, n = 26). The ewes were allowed to mate at estrus following the PGF2α injection. Pregnancy diagnosis was performed on day 30 after mating by ultrasonography. Group ratios for estrus (58.3%, 55.8%, 53.8%), conception (78.6%, 87.5%, 14.3%), lambing (90.9%, 90.5%, 50.0%), multiple births (15.0%, 31.6%, 0.0%), and average lamb number for birth (1.15%, 1.31%, 1.0%) were reported. In conclusion, the gonadotropin-supplemented protocols used here were found to be useful in ewes that were not pregnant after multiple matings during the breeding season in increasing the profitability of flocks with this problem.