The effect of injection of PMSG and GnRH hormones in estrus ‎synchronization program with progesterone sponge on ‎reproductive performance in Arabi ewes

The present study was performed to investigate the effect of injection of PMSG and GnRH hormones on reproductive performance of Arabi ewes in the breeding season. 75 ewes were divided into 5 groups. The first group had no estrus synchronization program and no hormonal injection (control). Vaginal progesterone sponge (MAP) was inserted into other groups for 14 days. Simultaneously with the withdrawal of sponge, they were treated with: 1- injection of 500 IU of PMSG, 2- injection of 100 micrograms of GnRH, 3- injection of 500 IU of PMSG plus 100 micrograms of GnRH and 4- without injection (MAP only). One healthy and fertile Arabi ram was assigned to each of the 5 ewes. Estrous behavior of ewes was recorded for 7 days. The estrous response, return to estrus, pregnancy length, lambing rate, prolificacy rate, fecundity rate and the ratio of the birth of male and female lambs, were not affected by treatments. Injection of PMSG and GnRH were able to reduce the time of estrus onset coMAPred to sponge treatment alone (P<0.05). The birth weight and weight of 30, 60 and 90 days in lambs, although were affected by the treatments (P<0.05), but no obvious effect of hormone injection was observed on these parameters. In general, the injection of PMSG and GnRH in the estrus synchronization program of Arabi ewes, although was an effective method in estrus onset time, but could not have a significant effect on the other reproductive performances of the animal during the breeding season.