The effect of different progesterone protocols on the reproductive efficiency of ewes during the non-breeding season

The effect of intra-vaginal Fluorogestone-Acetate (FGA) sponges (a progesterone analogue) +/- eCG (equine chorionic gonadotropin) oil the fertility of anestrous ewes was assessed. Ninety-six ewes were divided into 4 groups (24/group). The ewes were exposed to treatment for 6 days (FGA or FGA+eCG groups) and for 12 days (PGA or FGA+eCG groups). Sponges were withdrawn (day 0) and eCG (500 IU) or saline was injected. Ewes were examined for estrus and bred by fertile rams. Pregnancy was diagnosed by progesterone levels and ultrasound scanning. Estrous expression differed only between the FGA-eCG (12 days) and FGA (6 days) groups (P<0.05). Intervals from day 0 to onset of estrous were shorter (P<0.05) in the FGA-eCG (12 days) than those in the FGA (12 days) and FGA (6 days) groups. Progesterone levels were basal from day -10 through day 5 (<0.1 ng/mL) and increased gradually thereafter until day 20. Progesterone remained elevated through day 20 in 50, 75, 66.7 and 91.7% ewes treated for 6 days (FGA and FGA-eCG) or 12 days (FGA and FGA-eCG). Mean Values between eCG-treated versus non eCG-treated ewes were significant (P<0.01). From 68 pregnant ewes, 62 lambed at full term (150 days). No significant differences in pregnancy, lambing rate and number of newborns were found between eCG groups (6 or 12 days). Pregnancy rate from the first treatment was 70.8%. In conclusion, intra-vaginal FGA sponges with a 12 day+eCG regime Could adequately improve the reproductive performance of anestrous ewes. From the economic side, it is possible to replace them with a 6 day FGA+eCG regime bill with lower efficiency.