Metabolomic and Molecular Mechanisms of Glycerol Supplementation in Regulating the Reproductive Function of Kazakh Ewes in the Non-Breeding Season.

The activation mechanism of the reproductive axis in Kazakh ewes during the non-breeding season was explored by supplementation with glycerol complex (7% glycerol + tyrosine + vitamin B9). The experiment divided 50 ewes into five groups ( = 10). After 90 days of intervention, it was found that significant changes in serum DL-carnitine, N-methyl-lysine and other differential metabolites were observed in the GLY-Tyr-B9 group ( < 0.05, " < 0.05" means significant difference, " < 0.01" means "highly significant difference"). The bile acid metabolic pathway was specifically activated ( < 0.01). The group had a 50% estrus rate, ovaries contained 3-5 immature follicles, and HE staining showed intact granulosa cell structure. Serum E2/P4 fluctuated cyclically ( < 0.01), FSH/LH pulse frequency increased ( < 0.01), peak Glu/INS appeared on day 60 ( < 0.05), and LEP was negatively correlated with body fat percentage ( < 0.01). Molecular mechanisms revealed: upregulation of hypothalamic kiss-1/GPR54 expression ( < 0.01) drove GnRH pulses; ovarian CYP11A1/LHR/VEGF synergistically promoted follicular development ( < 0.05); the HSL of subcutaneous fat was significantly increased ( < 0.05), suggesting involvement of lipolytic supply. Glycerol activates the reproductive axis through a dual pathway-L-carnitine-mediated elevation of mitochondrial β-oxidation efficacy synergizes with kisspeptin/GPR54 signalling enhancement to re-establish HPO axis rhythms. This study reveals the central role of metabolic reprogramming in regulating seasonal reproduction in ruminants.