Ovarian activity in dairy Saanen goats subjected to a short-term ovulation induction protocol and a single injection of lecirelin (GnRH analog) given 28 h or 34 h after progestin pre-treatment

Abstract

Abstract Fixed-time artificial insemination (FTAI) and hormonal superovulation (SOV) are instrumental in enhancing genetic gain and productivity of commercial goat herds. The goal of this study was to document changes in antral follicle populations and ovulation in dairy Saanen does. Fifty-six animals received MAP sponges that were left in place for 6 days as well as 200 IU of eCG and 120 μg of cloprostenol i.m. 24 h before sponge withdrawal. Does were randomly divided into three groups: Gcon (n = 18) received 1 mL of saline 28 h after, whereas G28h (n = 19) and G34h (n = 19) received 25 μg of lecirelin i.m. 28 h or 34 h after sponge removal. Estrus was detected with intact bucks every 12 h and transrectal ovarian ultrasonography was carried out from the time of sponge removal until ovulation detection (8/8 h – 60 h after sponge removal) and then until 156 h after sponge withdrawal (12/12 h). There were no differences (P > 0.05) among GnRH-treated and control goats in estrus responses (G28h–57.9%; G34h–84.2%; Gcon–83.3%) and mean ovulation rates (G28h–100%; G34h–91.7%; Gcon–81.8%), but the intervals from MAP sponge withdrawal to ovulation and from the estrus onset to ovulation were less variable (P