The effect of GnRH and eCG administration during estrous synchronization on fecundity rate and percentage of prolificacy in Moghani ewes

During estrous synchronization, administration of gonadotropins, such as equine chorionic gonadotropin (eCG) after stopping progesterone treatment, increases the ovulation rate. Also, using gonadotropin-releasing hormone (GnRH) with eCG may cause an increase in ovulation and litter size in ewes. Therefore, this study's objective was to improve the fecundity rate and percentage of the prolificacy of Moghani ewes using GnRH and eCG administration during estrous synchronization in the non-breeding season. In the current study, ۲۰۰ ewes between ۲-۵ years old and weighing ۷۰ kg in a completely randomized design were allocated into two groups (۱۰۰ ewes/group). This study was performed in the non-breeding season under a natural photoperiod environment. To synchronize the estrous of the cycle, all ewes were treated for ۱۴ days with a controlled internal sponge device (CIDR). Ewes in the first (control) and second (eCG/GnRH) groups were intramuscularly injected with ۴۰۰ IU eCG and ۴۰۰ IU eCG with ۲.۵ ml GnRH, respectively, after sponge removal time. Then, the ewes were mated with Moghani rams. After parturition, each group's fecundity rate and prolificacy percentage were calculated. ProcGenmod analyzed the reproductive parameters using SAS ۹.۲ in a completely randomized design. The means of all reproductive traits were compared by using the Chi-Square test. The results showed that the control group had a lower fecundity rate (۷۲%) than the treatment group (۹۲%). In the eCG/GnRH group, the percentage of prolificacy was significantly different (P < ۰.۰۵) compared with control (۱۱۰.۸% vs ۱۲۴.۳%, respectively). Overall, the combined injection of GnRH and eCG caused improvement in the fecundity rate and percentage of prolificacy in the Moghani ewes compared to the infusion of only eCG in the non-breeding season, and it can be affordable in farm breeding conditions.

کلیدواژه ها:

ECG ، Estrous synchronization ، Fecundity rate ، GnRH ، Moghani ewes