Reproductive performance of seasonally anovular mixed-bred dairy goats induced to ovulate with a combination of progesterone and eCG or estradiol.

Abstract

Adult goats (n = 32) were randomly assigned to one of four treatments (n = 8, each): (i) progesterone (P4 ) + equine chorionic gonadotropin (eCG), treated with 25 mg progesterone intramuscularly (i.m.) + 250 IU eCG 24 h later; (ii) cronolone + eCG, treated with vaginal sponges - 20 mg cronolone × 7 days + 250 IU eCG at pessary removal; (ii) P4 + estradiol (E2 ), treated with 25 mg progesterone i.m. + 1 mg estradiol 24 h later; (iv) cronolone + E2 , treated with vaginal sponges - 20 mg cronolone × 7 days + 1 mg of estradiol i.m. at pessary removal. Goats were tested for estrus throughout the presence of a buck. Seven days prior and after treatment, an ovarian ultrasonographic scanning was performed to determine ovarian function and structures. An ultrasonographic pregnancy diagnosis was performed on day 30 post-service. In all groups, 100% estrus response was observed within 96 h post-treatment. While ovulation occurred in 100% of P4 + eCG and cronolone + eCG treated goats, the other groups only depicted 50% ovulatory activity (P < 0.05). Pregnancy rate was higher (P <0.05) in the P4 + eCG and cronolone + eCG groups (88 and 100%, respectively), compared with 38% in P4 + E2 and cronolone + E2 groups. The best treatments were those in which eCG was applied. The P4 + eCG treatment was a pessary-free, cheaper and effective protocol to induce ovulation in goats during the seasonal anovulatory period.