Reproductive performance changes in Lake and Torki Ghashghaei ewes by using eCG in nomadic breeding condition

This study was conducted to investigate the different doses of eCG on reproductive performance activities in Lake and Torki Ghashghaei ewes in spring season. In this study 75 Lake Ghashghaei ewes and Torki Ghashghaei ewes (3 to 4 years age) with the mean weight of 55±1.8 and 58±2.2 kgs were chosen respectively and divided into 5 treatment groups. The estrus cycle of the ewes were synchronized with progesterone sponges during a 14 days period. In each race one day before removing the sponges 300, 400, 500 and 600 eCG IU were injected to group two, three, four and five respectively and group one was assumed as control. The results showed that all of Lake Ghashghaei ewes in group three and four and Torki Ghashghaei ewes in group three, four and five showed estrus signs, after 48 h of removing sponges. Although there were not any significant differences (P>0.05) among different treatment groups in the percentage of pregnant ewes, but in group three of Lake Ghashghaei races and four of Torki Ghashghaei race had more pregnant ewes. In both races the groups which received eCG had more percentage of twining rate compared with control and the number of ewes with twin lambs increased after increasing the dose of eCG. In conclusion the results showed that in Lake and Torki Ghashghaei 400 and 500 eCG IU had the most effect on pregnancy and twining rate in spring season respectively.