Effect of eCG, PGF2α and GnRH hormones on ewe's reproductive performance in breeding season

The aim of this study was to determine the effects of eCG, PGF2α and GnRH hormone on improvement of reproduction performance of CIDR synchronized Zandi ewes in breeding season. 500 ewes with age of 2.5-4 years and same nutritional condition were selected for this study and received CIDR for 12 days. Then these ewes were assigned to five equal groups. First group received no hormone (control group). In the second group, ewes were injected 400 Iu of eCG at the time of CIDR removal. The ewes of third group received 400 IU of eCG and 1 ml PGF2α at the time of CIDR removal. The ewes of forth group received 400 IU of eCG at the time of CIDR removal and 1 ml GnRH in 14th day. The ewes of fifth group were received 400 IU of eCG and 1 ml PGF2α at the time of CIDR removal and 1 ml GnRH in 14th day. All ewes were inseminated 54 hours after CIDR removal. Results showed that heat rate was higher in hormone treated groups than control group (P<0.05), but the diffrences between treated groups were not significant. Groups receiving GuRHhad higher pregnancy rate, parturition rate and lambing rate than other groups (P<0.05). Pregnancy rate, parturition rate and lambing rate of eCG and PGF2α groups were higher than control group (P<0.05). In conclusion using of eCG injection at the time of CIDR removal and GnRH in the day of artificial insemination could improve reproductive efficiency in Zandi ewe in the breeding season.