ABSTRACT
This study was designed to determine the effect of estrus synchronization by either intravaginal progestagen sponges or prostaglandin F2α on estrus behavior, follicular growth patterns and concentrations of estradiol-17β (E2) and progesterone (P4) hormones in blood of Ossimi ewes. A total of 14 Ossimi ewes were randomly divided into two groups, 7 ewes each, balanced for body weight and parity. The first group, G1 synchronized by intravaginal progestagen impregnated sponges (40-mg fluorogestone acetate) for 14 days. While, the second group, G2, was synchronized by injecting two doses of 12.5 mg PGF2α (Dinoprost) 10 days apart. Estrus was observed after removing the vaginal sponges in G1 or after the 2nd PGF2α dose using two trained teaser rams and the ovaries were examined using ultrasonography technique to detect follicles ≥2 mm and corpus luteum (CL). Blood samples were collected via jugular vein to determine E2 and P4 concentrations in peripheral blood.
Estrus displaying time after the end of treatment, duration, ovulation time and estrous cycle length were significantly shorter (P<0.05) in G1 than G2. Moreover, diameter of ovulatory follicles and CL were larger in G1 (p<0.05). Ewes in G2 showed higher (P<0.05) number of preovulatory follicles than G1.Ovulation rate was similar in the two groups. E2 level was higher (P<0.05) in G1 during day 0 and P4 level during days 10 and 14 of the estrous cycle than that in G2.
In conclusion, ewes synchronized by intravaginal progestagen sponges improved estrus expression and ovulation time, in addition to that the estrus duration were shorter. The diameter of ovulatory follicles and CL were larger but the number of the preovulatory follicles was less and not affected on ovulation rate when compared with ewes synchronized by PGF2α.