Evaluation of follicular and progesterone and oestradiol changes concentrations during the estrus cycle of Naeini's ewes

This study was conducted to evaluate the follicular and hormonal changes of Naeini ewes during the estrous cycle in breeding season. For this purpose, eight Naeini ewes were selected from a purebred herd in the fall of 1392. The estrous cycle of all ewes was synchronized with insertion of intravaginal progesterone sponge during a 12 days period. The ewes were checked for estrus signs using 4 intact rams fitted with aprons. Then the ovarian follicles changes were evaluated by ultrasound method during a 16 days period after estrus detection. At the same time, blood samples were collected to determine concentration of serum progesterone and oestradiol. Results showed that six ewes had single ovulation and two ewes had double ovulation. In present study, the right ovary was more active than the left ovary. The small and medium follicles were minimum during the early and late of estrus cycle, while the large follicles were maximum at the end of this cycle (P