The potential effect of intravenous administration of glutamate on the ovarian activity and the LH secretion pattern, considering the anestrous yearling goat as an animal model, were assessed. In late April, yearling goats (n = 20) were randomly assigned to either (1) Glutamate supplemented (GLUT; n = 10, Live Weight (LW) = 29.6 ± 1.02 kg, Body Condition (BCS) = 3.4 ± 0.2 units; i.v. supplemented with 7 mg GLUT kg⁻¹ LW) or (2) Non-supplemented (CONT; n = 10; LW = 29.2 ± 1.07 kg, BCS = 3.5 ± 0.2 units; i.v. saline). The oats were estrus-synchronized; blood sampling (6 h × 15 min) was carried out for LH quantification. Response variables included pulsatility (PULSE), time to first pulse (TTFP), amplitude (AMPL), nadir (NAD), and area under the curve (AUC) of LH. Ovaries were ultra-sonographically scanned to assess ovulation rate (OR), number of antral follicles (AF), and total ovarian activity (TOA = OR + AF). LH-PULSE was quantified with the Munro algorithm; significant treatment x time interactions were evaluated across time. The variables LW and BCS did not differ (p > 0.05) between the experimental groups. Nevertheless, OR (1.77 vs. 0.87 ± 0.20 units), TOA (4.11 vs. 1.87 ± 0.47 units) and LH-PULSE (5.0 vs. 2.2 pulses 6 h-1) favored (p < 0.05) to the GLUT group. Our results reveal that targeted glutamate supplementation, the main central nervous system neurotransmitter, arose as an interesting strategy to enhance the hypothalamic–hypophyseal–ovarian response considering the anestrous-yearling goat as an animal model, with thought-provoking while promising translational applications.

The neuroendocrine regulation of the seasonal reproductive axis requires the integration of internal and external signals to ensure synchronized physiological and behavioral responses. Seasonal reproductive changes contribute to intermittent production, which poses challenges for optimizing goat product yields. Consequently, a significant objective in seasonal reproduction research is to attain continuous reproduction and enhance profitability in goat farming. Glutamate plays a crucial role as a modulator in several reproductive and metabolic processes. Hence, the aim of this study was to evaluate the potential impact of exogenous glutamate administration on serum insulin concentration and ovarian function during the out-of-season period in yearling goats. During the anestrous season, animals were randomly located in individual pens to form two experimental groups: (1) glutamate (n = 10, live weight (LW) = 29.1 ± 1.02 kg, body condition score (BCS) = 3.4 ± 0.2 units) and (2) control (n = 10; LW = 29.2 ± 1.07 kg, BCS = 3.5 ± 0.2), with no differences (p < 0.05) regarding LW and BCS. Then, goats were estrus-synchronized, and blood sampling was carried out for insulin quantification. Ovaries were ultrasonographically scanned to assess ovulation rate (OR), number of antral follicles (AFs), and total ovarian activity (TOA = OR + AF). The research outcomes support our working hypothesis. Certainly, our study confirms that those yearling goats treated with exogenous glutamate displayed the largest (p < 0.05) insulin concentrations across time as well as an augmented (p < 0.05) out-of-season ovarian activity.

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.