Effect of Different Time Artificial Inseminations on Reproductive Performance of Taleshi Ewes

The objective of this study was to determine the best time for artificial insemination in Taleshi ewes. One hundred and fifty ewes were randomly allotted to three groups (n=50/per group). Estrus was synchronized with intravaginal insertion of Controlled Internal Drug Release (CIDR) for 14 days. At the time of CIDR removal PMSG (300IU) was injected to the ewes. The first (AI28), second (AI40) and third (AI52) groups were inseminated (cervically) 28, 40 and 52 hours after CIDR removal, respectively. All ewes showed estrus singns about 24 hours after CIDR withdrawal. The results of insemination efficiency and reproduction performance indicated that in prolificacy and twin bearing traits there did not exist any statistical difference among the groups. Insemination efficiency, lambing rate and fertility made significant differences among the groups (P<0.05). Insemination efficiency in AI40 and AI52 amounted to 50% and 38% respectively, which was significantly different (P<0.05) from AI28 (18%) treatment. Lambing rates in AI40 and AI52 were 58% and 38% respectively, statistically different (P<0.05) from AI28 treatment. The results of the research indicated that the most appropriate time for Taleshi ewes insemination was between 40-52 hours after CIDR removal.