The effect of time and doses of PMSG hormone injection on reproductive efficiency of Farahan ewes syncronized with CIDR

The aim of this study was investigated the effect of synchronization with different PMSG dosages and time of hormone injection and its effect on changes in steroid hormones (E2 and P4) in Farahani ewes breed. Seventy Farahani ewes used in this study. Treatment included: T1: injection of 400 IU PMSG 24h before CIDR removal, T2: injection of 500 IU PMSG 24h before CIDR removal, T3: injection of 600 IU PMSG 24h before CIDR removal, T4: injection of 400 IU PMSG in CIDR removal time, T5: injection of 500 IU PMSG in CIDR removal time, T6: injection of 600 IU PMSG in CIDR removal time, Control: no injection in CIDR removal time. After withdrawal CIDR, estrous percentage, pregnancy rate and parturition assessed. The results of this experiment showed that the conception rate was similar in all groups and there was no significant effect in lamb weight among all treatments. The number of lamb per ewe was significant between T2 and others groups (P˂0.05). The progesterone levels were significantly (P<0.01) increased from day 0 to day 50. Higher progesterone levels were recorded in all groups of ewes and non-significant between groups. In general, administration 500 IU of PMSG 24 hours before CIDR removal improved estrous percentage, pregnancy rate and parturition in ewes. Keywords: Estrous synchronization, PMSG, Steroid, Ewe