Evaluating the role of hCG, GnRH and progesterone in Enhancing Fertility in Estrus Synchronized Ewes

This study aimed to evaluate the effect of hCG, GnRH, and progesterone administration at day 4 following synchronization on reproductive performance of estrus‐synchronized ewes. In addition, to determine the relationship between these hormonal treatments and serum progesterone concentrations. Thirty‐two ewes were synchronized using intra vaginal sponges. At sponge withdrawal, 625 IU of PMSG was given for each ewe. Ewes were randomly set into four groups of eight. On day 4 post–natural mating, treatment was as follows: Group G1 (control) received normal saline, GroupG2 received500 IU hCG, Group G3, 0.0042 μg GnRH was administered; and Group G4 received 50 mg progesterone. Pregnancy was diagnosed by a rectal ultrasound probe. On days 0, 12, 22, and 32, blood samples were collected for ELISA test. Results, reproductive performance including estrus response, conception rate, and litter size improved in the ewes treated by progesterone, HCG or GnRH in comparison with control ewes. In the treatment groups, estrus appeared and the conception rate reached to 100%, in contrast to 90% in control group. Moreover, the likelihood of twin births was 4.58 times greater in the hCG group. Progesterone levels increased in all groups on days 12, 22, and 32 post–synchronization. Notably, the hCG treated ewes demonstrated the most pronounced progesterone increases on days 22 and 32, followed by the GnRH and progesterone groups. This study concluded that the applied HCG on day 4th post estrus synchronization stimulated the early formation of corpus lutem and increased reproductive performance, litter size and progesterone level.