The effects of different eCG doses on reproductive performance in Torki-Ghashghaei ewes in autumn season

Reproductive performance is the most important economic trait in sheep production and it can be manipulated by using hormonal treatments. Equine chorionic gonadotropin (eCG) is widely used for improving the fertility in ewes. In some studies the use of low and high doses of this hormone increased number and the size of large follicles and also it could enhance the ovulation rate, but it decreased pregnancy rate. As it was not found any report about the effect of using eCG on reproductive performance of Torki-Ghashghaei ewes, this study was conducted to investigate the effect of different dose of eCG on estrus response, estrus onset, pregnancy rate and twining rate of these ewes in autumn season.
In this study, the total of 75 cyclic ewes with the mean weight of 573.6 kgs were randomly assigned to five experimental groups (n=15/group). The estrous cycle of all ewes was synchronized with the insertion of intravaginal progesterone sponges during a 12 days period. One day before withdrawaling progesterone sponges 300, 400, 500 and 600 IU eCG were injected intramuscularly to ewes in group Π, Ш, ΙV and V, respectively and the group Ι (without eCG injection) was used as control group. The reproductive variables such as: time of estrus onset (hour), estrous response, pregnancy rate, twining rate, fecundity and prolificacy rate were measured in this experiment.
Estrous responses for all eCG recipient ewes (100%) were significantly higher (P Generally, the results showed that injecting 600 IU eCG had the most effect on increasing pregnancy rate and twining rate in Torki-Ghashghaei ewes in autumn season.