OVULATION SYNCHRONIZATION IN eCG-TREATED GOATS AFTER A PGF??-BASED SHORT TIME PROTOCOL DURING THE BREEDING SEASON

Abstract

The aim of this study was to evaluate whether the administration of 100 IU of equine chorionic gonadotropin (eCG) or human chorionic gonadotropin (hCG) at the time of the second injection of a double prostaglandin F?? (prostaglandin PGF2?) protocol, applied 7 days apart, improves the synchronization of estrous activity and ovulation in goats. Twenty-four cyclic goats were assigned to three groups (n = 8 each). All animals received two doses of 5 mg PGF?? (DIN), 7 days apart; at the time of second injection, they were treated with 100 IU of eCG (PG-eCG), 100 IU of hCG (PG-hCG), or no additional hormone (PG). Although the initial absolute estrous response at 36 h was similar between PG and PG-eCG groups, the PG-eCG treatment achieved a higher cumulative estrous response by 48 h and maintained this advantage at later timepoints (75 and 87.5%, respectively; p 0.05). Follicular monitoring revealed that, in does of the PG–eCG group, eCG administration promoted a more coordinated preovulatory follicular development, particularly between 36 and 72 h after the second DIN injection, and resulted in a concentrated ovulatory peak between 60 and 72 h. This pattern indicates superior synchronization compared with the broader ovulatory window observed in the PG group (36–96 h). In the hCG-treated group, the ovulatory response was distributed across a wide time window, from 36 to 84 h; furthermore, a null response to the treatment was also observed. There were no significant differences in estrous or ovulatory response between the PG and PG-eCG groups (p 0.05); however, both showed higher responses compared with PG-hCG (p 0.05). Goats treated with 100 IU of eCG after a synchronization treatment with a PGF2? analogue showed a better estrous (shorter presentation time) and ovulatory responses. Therefore, it can be an alternative to make hormonal treatments more efficient at low cost. It can also be implemented in FTAI (fixed-time artificial insemination) protocols to positively impact on reproductive parameters.