Effect of subsequent two short-term, short-term, and long-term progestagen treatments on fertility of Awassi ewes out of the breeding season

Abstract

The aim of this study was to evaluate the effectiveness of different treatment methods of progestagen with PMSG in Awassi ewes out of the breeding season. A total of 48 ewes were divided into four groups equally. In Group I, vaginal sponges (30 mg fluorogestone acetate; FGA) were administered to ewes for seven days; afterwards vaginal sponge removal at the end of rh days and new vaginal sponge replaced for seven days in the same group. Vaginal sponges were administered for 7 days and 14 days in Group II and Group III, respectively. Group IV (Control) served as control group. In all experimental groups, 500 IU PMSG was given at sponge removal. Parameters such as estrus response rate, pregnancy and lambing rates, interval from sponge withdrawal to onset of estrus, duration of estrus and fecundity were evaluated. There were no significant differences in terms of estrus response rate, pregnancy rate, lambing rate, and fecundity between the Group I, II and III (p>0.05). In addition to this, any difference in the duration of estrus was not observed in all groups. However, variations in the interval from sponge removal to estrus was found significant (p<0.05) differences between Group II (53 +/- 3.37 h) and Group III (41.5 +/- 1.81 h). A slight increase in progesterone levels was observed after ram introduction, but a significant decrease in progesterone levels was found after two weeks from ram introduction (p<0.05). It was concluded that there was no advantage of using two subsequent sponge treatments for achieving high progesterone concentration during treatment. In addition, short-term sponge treatment (7d) was found as effective as long-term sponge treatment in Awassi ewes out of the breeding season.