The anti-heat stress effects of Chinese herbal medicine prescriptions and rumen-protected γ-aminobutyric acid on growth performance, apparent nutrient digestibility, and health status in beef cattle.

This study aims to evaluate the anti-heat stress effect of Chinese herbal medicine (CHM) prescription, rumen-protected γ-aminobutyric acid (RP-GABA), and CHM plus RP-GABA co-medication on growth performance, apparent digestibility, and serum parameters in heat-stressed beef cattle. Forty beef cattle were randomly divided into four groups. Control group was supplied with basal diet, while CHM, γ-aminobutyric acid (GABA), and CHM + GABA groups were, respectively, supplied with CHM, RP-GABA, and CHM plus RP-GABA in basal diet. Our result indicated that CHM + GABA elevated apparent digestibility including crude protein, Ca, P, crude fat (CF) (p < .01), and neutral detergent fiber (NDF) (p < .05), but no difference was found with CF and NDF digestibility both in CHM and GABA group (p > .05). More importantly, average daily gain (ADG) was improved in CHM, GABA, and CHM + GABA groups, while average daily feed intake (ADFI) significantly increased only in CHM + GABA groups (p < .05). Meanwhile, CHM + GABA displayed notably more positive effect in serum hormones, immune globulin, ions contents, and blood inflammatory cytokines than other treatment groups and control group. These results demonstrated that both CHM and GABA are effective in alleviating heat stress response and the co-medication has a synergistic effect on anti-heat stress.