Dietary Rumen-Protected Taurine Enhances Growth Performance and Meat Quality in Heat-Stressed Crossbred Gan-Xi Goats via Modulating GLUT4/PYGM-Mediated Muscle Energy Metabolism

Heat stress induced by high temperature and humidity in southern China during summer reduce goat production efficiency and meat quality. Taurine (TAU), one of the most abundant amino acids in animal tissues, plays a vital role in alleviating heat stress and regulating energy metabolism through its involvement in glucose uptake and glycogen turnover. This study aimed to investigate the effects of rumen-protected (RP)-TAU on the meat quality, hepatic gluconeogenesis, and muscle energy metabolism of heat-stressed goats. During summer, twenty-four male crossbred Gan-xi goats (20.45 ± 2.95 kg) aged 5 months were randomly allocated to two groups treated with or without 0.4% RP-TAU (on a diet weight basis). After feeding for 60 days, six goats per treatment were slaughtered. Compared with the control group, RP-TAU supplementation significantly improved the growth performance of goats, as evidenced by increased final body weight, average daily gain, and average daily feed intake (p < 0.05). The goats in the RP-TAU group showed a reduced splenic index (p < 0.05), lower serum cortisol levels (0.05 < p < 0.1), and decreased muscle crude fat content (p < 0.01). Crucially, meat quality was improved with reduced hardness, gumminess, and chewiness (p < 0.05), indicating better textural properties. Nutritionally, RP-TAU supplementation modulated the muscle fatty acid profile, significantly reducing the concentrations of palmitic (a saturated fatty acid), palmitoleic (a monounsaturated fatty acid), and nervonic acids (p < 0.05), while cystine content was reduced (p < 0.05). RP-TAU supplementation significantly enhanced the muscle contents of glucose and glycogen, glycolytic potential, phosphofructokinase activity, and ATP level, while decreasing the pyruvate level and AMP/ATP ratio (p < 0.05). Gene expression analysis revealed the upregulation of GLUT4 and PYGM and the downregulation of GSK3β in muscle (p < 0.05). These results indicated that dietary supplementation of RP-TAU might be beneficial to improve stress resistance and meat quality by increasing muscle energy supply and glucose uptake in Gan-xi goats.