Effects of adding equine chorionic gonadotropin (eCG) to cloprostenol-based estrus synchronization protocol on luteogenesis, pregnancy rate, and embryo development in cyclic dairy goats

This study assessed, in cyclic goats, the impact of adding eCG to a cloprostenol-based estrus synchronization protocol on follicular, ovulatory, and luteal dynamics, as well as pregnancy rates and embryo outcomes after non-surgical recovery. Dairy goats received two doses of 131.5 μg of cloprostenol at 7.5-day intervals, with 100 IU of eCG (G-eCG, n = 49) on D7.5 or without (G-saline, n = 56). Estrous response, interval from second dose of cloprostenol to onset of estrus, interval from onset of estrus to ovulation, interval from second dose of cloprostenol to ovulation, animals ovulating, diameter of the ovulatory follicle, number of CL and pregnancy rates were similar (P > 0.05) between the groups, but variance was lower (P < 0.05) in the G-eCG group for the intervals from estrus onset to ovulation (960.9 vs 64.0 h) and from the second dose of cloprostenol to ovulation (1348.4 vs 448.4 h). Luteal area and the vascularized luteal area were significantly larger (P < 0.05) in the G-eCG (2.38 ± 0.11 cm² and 0.45 ± 0.02 cm², respectively) compared to the G-saline (1.88 ± 0.09 cm² and 0.35 ± 0.03 cm², respectively). No differences (P > 0.05) were found between groups for any major efficiency parameter related to non-surgical embryo collection, except for the viable embryo rate, which was significantly higher (P < 0.05) in the G-eCG (100 %) compared to the G-saline (40 %). Adding 100 IU of eCG to the synchronization protocol can enhance estrus synchrony, ovulatory, and luteal parameters, improving conditions for TAI and embryo development in dairy goats.