Effects of exogenous oxytocin on cervical penetration of Iranian ewes

Abstract

The objective of this study was to determine the effect of exogenous oxytocin (OT) treatments on the cervix dilation of three breeds of Iranian ewes. Cervix dilation was measured by transcervical passage of scaled bovine catheter into the uterus of the ewes. Fifty four healthy Zandi ewes were equally assigned to six groups in the late breeding season. Thirty healthy Lori-bakhtiari breed ewes were equally assigned to six groups during anestrous. The ewes received 100, 80 and 60 IU of intravenous (i.v) and intramuscular (i.m) OT. In the breeding season, 120 healthy Zell breed ewes were equally assigned to six groups and received 150, 100 and 50 IU of i.v and i.m OT. Cervix dilation was examined before OT injection 10 to 15 min following treatment. This study indicates that injection of more than 80 IU OT can completely dilate the cervix of Iranian ewes (P < 0.05) and the reproductive seasons (anestrous, late breeding season and breeding season) and the type of injection (i.v or i.m) has no significant effect on induced cervix penetration by OT. Therefore, this dose is the applicable dose for the cervix dilation and transcervical artificial insemination and embryo recovery in Iranian ewes.

Key words: Iranian ewes, oxytocin, cervical dilation, transcervical artificial insemination, transcervical embryo transfer.