Comparison of Different Methods of Oestrus Synchronization on Reproductive Performance of Farahani Sheep in Iran

This experiment was carried out on 123 Farahani ewes from a herd in Delijan city in Markazi province of Iran to determine the best short-term method for oestrus synchronization. Ewes were divided into five experimental groups randomly: group 1) use of controlled intervaginal drug release devices (CIDR) for 7 days with intramuscular (IM) injection of PGF2α on zero day and IM injection of 500 IU equine chorionic gonadotropin (eCG) at the time of CIDR removal; group 2) use of CIDR for 7 days and IM injection of PGF2α on the 6th day and IM injection of 500 IU eCG at the time of CIDR removal; group 3) use of intravaginal sponge for 7 days with IM injection of PGF2α on zero day and IM injection of 500 IU eCG at the time of sponge removal; group 4) use of intravaginal sponge for 7 days with IM injection of PGF2α on the 6th day and IM injection of 500 IU eCG at the time of sponge removal and group 5) control, without any treatment. Results showed that parturition percentage on expected date was almost doubled in all treatment groups when compared to control group. Each treatment used for oestrus synchronization increased the percentage of twinning on expected date in comparison with control group. Obtained results indicated that the most ewes lambed on expected date after 7 day treatment with both the intra-vaginal sponge and CIDR, and had a favorable impact on fertility of ewes.