The aim of this study was to evaluate the possible effect of two doses of hCG (100 and 300 IU) applied at two different times (7 and 14 d) after a fixed-time artificial insemination protocol (FTAI) upon some variables involved in the embryonic implantation rate in goats during the natural deep anestrous season (April, 25° north). The experimental units considered crossbred, multiparous, anovulatory goats (n = 69, Alpine, Saanen, Nubian x Criollo), with average body weight (43.6 ± 5.7 kg) and body condition score (1.86 ± 0.28 units) located in northern–semiarid Mexico (25° N, 103° W). Once the goat’s anestrus status was confirmed, goats were subjected to an estrus induction protocol. Upon estrus induction confirmation, goats (n = 61) were subjected to a FTAI procedure. Immediately after the FTAI, the goats were randomly distributed to five experimental groups: (1). G100-7 (n = 13) 100 IU, hCG 7 d post-FTAI, (2). G100-14 (n = 12) 100 IU hCG, 14 d post-FTAI, (3). G300-7 (n = 12) 300 IU, hCG, 7 d post-FTAI, (4). G300-14 (n = 12) 300 IU hCG 14 d post-FTAI, and (5). Control group, CONT (n = 12) 0.5 mL saline, 7 and 14 d post-FTAI. The response variables conception rate (39.36 ± 0.23), fertility rate (27.96%), prolificacy rate (1.1 ± 0.29 kids), ovulation rate (0.74 ± 0.20 corpus luteum) corpus luteum diameter (10.15 ± 0.59 mm), embryo number (1.58 ± 0.20), and embryo implantation rate (48.96%), did not differ between treatments. However, while the variables fecundity rate (67%), embryo efficiency index-1 (33.99 ± 0.20%), and embryo efficiency index-2 (27.94 ± 0.30%) were favored by the G300-14 treatment, the corpus luteum area was favored (p < 0.05) by both G300-7 (113.30 ± 0.19 mm²) and G300-14 (103.04 ± 0.17 mm²). Such reproductive strategy emerges as an interesting approach, not only to enhance the out-of-season reproductive outcomes, but also to boost one of the main rulers defining the global reproductive efficiency of a heard, namely, the embryo implantation efficiency.

The objective of this research was to evaluate the effect of two doses of hCG (100 and 300 IU) administered at two different times after fixed-time artificial insemination (FTAI) on some response variables related to early fetal loss and total litter weight in goats during the reproductive transition period. Crossbred multiparous goats (n = 40) were subjected to an estrus induction protocol, subsequently inseminated, and randomly distributed into five experimental groups (n = 8): (1). G100-7, 100 IU hCG, 7 d post FTAI; (2). G100-14, 100 IU hCG, 14 days post FTAI; (3). G300-7, 300 IU hCG, 7 d post FTAI; (4). G300-14, 300 IU hCG, 14 days post FTAI; and (5). CONT, 0.5 mL of saline solution, 7 and 14 days post FTAI. The variables of corpus luteum area, embryonic implantation rate, embryonic efficiency index 1 and 2, conception rate, fertility rate, fecundity rate, fetal losses at days 30 and 45, total fetal losses, and the total weight of the litter favored G300-14. The use of hCG (300 IU) in the reproductive transition period is an effective reproductive strategy, reducing early fetal losses, improving embryonic efficiency, and increasing total litter weight, all of which are fundamental to the reproductive success of marginal goat production systems.