Gamma-Aminobutyric Acid Modulates Buck Semen Quality and Sperm Preservation Duration In Vivo and In Vitro

Improving sperm motility and preservation duration is crucial for enhancing reproductive efficiency in dairy goats. Given the decline of gamma-aminobutyric acid (GABA) during in vitro storage, this study evaluated its effects and mechanisms on buck semen via diet and extender supplementation. Dietary GABA supplementation significantly increased ruminal total volatile fatty acids (P < 0.01) and ammonia nitrogen levels (P < 0.05), enriched beneficial bacteria, enhanced serum antioxidant capacity (P < 0.05), and improved sperm motility, velocity, acrosome and plasma membrane integrity (P < 0.05). Although GABA did not cross the blood-testis barrier, it significantly elevated serum LH and testosterone levels (P < 0.01). In the in vitro preservation experiment, adding 1.0 g/L GABA to the extender significantly improved sperm viability, kinematic parameters, antioxidant capacity, acrosome and membrane integrity on days 3 and 5 of storage (P < 0.05), while reducing reactive oxygen species (ROS) and malondialdehyde (MDA) levels (P < 0.05). Proteomic analysis revealed that GABA upregulated membrane structure-related proteins, and PLA2G10-mediated changes in phospholipase A2 (PLA2) activity were identified as a key mechanism by which GABA modulates sperm membrane structure and motility. Inhibition of PLA2G10 with LY329722 significantly abrogated the protective effects of GABA (P < 0.01). GABA not only indirectly improves buck semen quality by modulating the rumen microbiota and hypothalamic-pituitary-testicular axis, but also directly enhances in vitro sperm preservation through PLA2G10-mediated membrane remodeling. GABA can serve as a functional feed additive and a semen extender protectant to effectively improve reproductive management in ruminants.