The effect of melatonin on estrus induction and reproductive performance of Taleshi ewes in non-breeding season

The purpose of this study was to investigate the effect of melatonin on estrus induction and reproductive performance of Taleshi ewes in non-breeding season (February to April). Sixty non-pregnant and non-lactating ewes (2-4 years old and 37±5 kg BW) were randomly allocated into four groups (n=15/group). Control group did not receive any treatment. In the second group، ewes received CIDR and PMSG and the third group were treated by melatonin، CIDR and PMSG. The fourth group، ewes received only melatonin implant at the base of ear. In the third and fourth groups، ewes received melatonin، 11 days after separation of rams from the flock (0 day) and in groups two and three، CIDR were inserted on day 45. On day 59، at the time of CIDR withdrawal، PMSG (500 IU) were injected (i. m). On day 60 rams were introduced to the flock. In groups two and three، interval between ram introduction and estrus were reduced (P<0. 05). In group four، interval between ram introduction and estrus took 43 days however، this effect was not statistically different with control group. Estrus percentage in second and third groups were significantly higher than control group (P<0. 05). Lambing efficiency، prolificacy and lambing rate in treatment groups were significantly higher than control group (P<0. 05). It is concluded that implantation of melatonin with CIDR and PMSG treatment can induce estrus and increase reproductive performance of Taleshi ewes in non-breeding season.