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.
Highlights
Sheep breeding in Turkey is mostly done for producing meat from lamb production
One of the factors contributing to the problems above may be the inadequate development of a follicle, which leads to either ovulation failure or poor development of the corpus luteum (CL) and impaired progesterone synthesis or bad quality embryos that fail to result in pregnancy
This study focuses on ewes that were not pregnant after multiple matings while in heat they previously had fertile seasons
Summary
Each ewe is important in this business; most sheep breeds, such as Merino and Akkaraman, are low prolific. These breeds usually have low ovulation rates but are very well adapted to the environmental conditions in Turkey. To alleviate these problems, animals are supplemented with exogenous hormones to ensure ovulation and better CL and embryo development. For this purpose, there are two commonly used hormones: gonadotropin-releasing hormone (GnRH) and human
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