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 notbecome pregnant during the breeding season after at least 3 matings. Nonpregnant Middle Anatolian Merino ewes (n = 117) were givena 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 allowedto mate at estrus following the PGF2α injection. Pregnancy diagnosis was performed on day 30 after mating by ultrasonography. Groupratios 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-supplementedprotocols used here were found to be useful in ewes that were not pregnant after multiple matings during the breeding season inincreasing the profitability of flocks with this problem.