The effect of equine chorionic gonadotrophin (ecg) injection combined with prostaglandin F۲α (pGF۲α) and gonadotrophin releasing hormone (GnRH) treatment on reproductive performance of Zandi ewes during non-breeding season

In this study, we aimed to investigate reproductive performance in estrus-induced Zandi ewes treated with equine chorionic gonadotrophin (eCG) injection in combination with prostaglandin F۲α (PGF۲α)and gonadotrophin releasing hormone (GnRH) during non-breeding season. The estrous cycle was synchronized using controlled internal drug release (CIDR) for ۱۲ days. The ewes were randomly assigned to five groups (n=۱۰۰ in each group). The first group (control) did not receive hormone injection, the second group (eCG) received ۴۰۰ IU of eCG at the time of CIDR removal, the third group (eCG+PGF۲α) received ۴۰۰ IU of eCG and ۱ ml of PGF۲α at the time of CIDR removal, the fourth group (eCG+GnRH) received ۴۰۰ IU of eCG at the time of CIDR removal and ۱ ml of GnRH injection on the day of insemination, and the fifth group (eCG+PGF۲α+GnRH) received ۴۰۰ IU of eCG, ۱ ml of PGF۲α at the time of CIDR removal, and ۱ ml of GnRH on the day of insemination. The results showed that the heat response rate was higher in all the groups receiving hormonal injections compared with the control group (P<۰.۰۵). In addition, the lambing and parturition rateswere significantly (P<۰.۰۵) higher in the groups receiving GnRH compared with other treatments.In fact, in groups receiving eCG and PGF۲α, lambing and parturition rateswere higher than the control group (P>۰.۰۵). In conclusion, use of eCG at the time of CIDR removal and GnRH on the day of insemination increased reproductive performance. Therefore, it can be applied as a strategy for increasing lambing rate in ewes.

Keywords:

Lambing rate , eCG , GnRH , PGF۲α , Zandi ewes