effects of short-term treatment with progesterone and pgf2∝ injection time on reproductive performance of farahani ewes in breeding season.

this experiment were carried out to compare different short-term oestrous synchronization methods in farahani ewes to determine of the best method, so were used 123 ewes from a herd in delijan city in markazi province. after ensuring their health, ewes were divided  to five experimental groups randomizely. the oestrous cycles of the ewes were synchronized using these five methods: 1) use of cidr for 7 days, with an intramuscular (i.m.) injection of pgf2 in zero day, and i.m. injection of 500 iu pmsg at the time of  cidr remoal, 2) use of cidr for 7 days, and an i.m. injection of pgf2  at 6th day, and i.m. injection of 500 iu pmsg at the time of cidr removal, 3) use of sponge for 7 days, with an i.m. injection of pgf2  in zero day, and i.m. injection of 500 iu pmsg at the time of sponge removal, 4) use of sponge for 7 days, and with an i.m. injection of pgf2  at 6th day, and i.m. injection of 500 iu pmsg at the time of sponge removal, 5) control, without progesterone treatment (cidr of sponge) and injection of pmsg and pgf2 . results were shown that parturition percentage during expected date were 86.95, 86.95, 85.15 , 92 and 48 respectively. these differences were significant between control group with other groups (p<0.01) , but were not significant among four groups, and highest percentage was related to fourth group. lambing percentage for five groups during expected date were 95.65, 95.65, 96.29, 104 and 48 respectively, that differences among first, second, third and fourth groups were not significant but it was significant between control group with other groups (p<0.01). percentage of twining during expected date were 10, 10, 13, 13 and 0, respectively, that these differences were not significant and the highest  percentage related to third and fourth groups. result indicated ewes parturition during expected date were done in period time of 7 days, and using both the intravaginal sponge and cidr in the short-term treatment, had a favorable impact on fertility and lambing ewes.