Creatine pyruvate and gamma-aminobutyric acid mitigate heat stress in goats: Mechanistic insights from antioxidant function, ruminal epithelial barrier integrity, and transcriptomics.

Heat stress is a major environmental factor limiting goat productivity. This study investigated the regulatory effects of creatine pyruvate (CrPyr) and γ-aminobutyric acid (GABA) on the antioxidant capacity and ruminal epithelial barrier function of goats under heat stress. A total of 54 Jianzhou large black goats, 4 months old with an average weight of 22.61 ± 0.47 kg, were randomly assigned to three groups: a control group (basic diet), a CrPyr group (basic diet with 0.4% CrPyr), and a GABA group (basic diet with 0.016% rumen-protected GABA). All goats were housed in an environment with temperatures ranging from 32 °C to 38 °C for 60 days. Physiological, serum, and ruminal parameters were measured. Results indicated that after 60 days, both CrPyr and GABA supplementation significantly increased serum levels of immunoglobulins (IgM, IgG) and decreased malondialdehyde (MDA) (P < 0.05). The CrPyr group exhibited elevated triiodothyronine (T3) and thyroxine (T4), while the GABA group showed higher T4 and glutathione peroxidase (GSH-Px) activity (P < 0.05). Ruminal epithelial morphology was improved in both treatment groups, evidenced by increased granular layer thickness in the dorsal rumen and decreased stratum corneum thickness in the ventral rumen (P < 0.05). Additionally, mRNA expression of pro-inflammatory cytokines (IL-1β, TNF-α) was downregulated, whereas expression of the anti-inflammatory cytokine IL-10 and tight junction proteins (Claudin-1, Occludin, ZO-1) was upregulated in the ruminal epithelium (P < 0.05). Transcriptome and KEGG analyses revealed that differentially expressed genes (e.g., ENO2, TNFAIP3) were primarily enriched in pathways related to energy metabolism, immune regulation, and oxidative stress, contributing to enhanced ruminal barrier function and heat stress adaptation. In summary, dietary supplementation with CrPyr or GABA enhances systemic antioxidant and immune capacity, promotes the repair of heat stress-induced ruminal epithelial damage, optimizes barrier function, and consequently mitigates the adverse effects of heat stress in goats.