Effect of estradiol and oxytocin on ovine cervical relaxation

Abstract

The aim of this study was to examine the effect of estradiol (E2) and oxytocin (OT) treatments on the cervix dilation of three breeds of Iranian ewes. Cervix dilation was measured by penetration of scaled bovine catheter into the cervix of the ewes. In experiment 1, 60 Zell ewes were equally assigned to three groups in the breeding season. At first, the ewes received 100 μg intravenous (i.v) E2. 12h later, the ewes received 150, 100, and 50 IU OT. In experiment 2, 27 Zandi ewes were equally assigned to three groups in late breeding season and after jugular E2 injection, received 100, 80, and 60 IU OT. In Experiment three, 15 Lori-bakhtiari ewes were equally assigned to three groups during anestrous season and received 100, 80, and 60 IU OT after jugular E2 reception. Cervix dilation were examined before and 10 to 15 min after E2 and OT injection. This study indicates that just E2 had no effect on cervix dilation but injection of E2 and more than 80 IU OT can completely dilate the cervix of Iranian ewes (P < 0.05). Reproductive seasons (anestrous, late breeding season and breeding season) have no significant effect on induced cervix dilation by E2 and OT. In conclusion, this is good procedure for improve cervix relaxation and perform transcervical artificial insemination and transcervical embryo transfer in ewes.

Key words: Ewes, Estradiol, Oxytocin, Cervical dilation.