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.

中文翻译：

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中草药方剂和过瘤胃保护γ-氨基丁酸对肉牛生长性能、养分表观消化率和健康状况的抗热应激作用。

本研究旨在评估中草药 (CHM) 处方、过瘤胃保护 γ-氨基丁酸 (RP-GABA) 和 CHM 加 RP-GABA 联合用药对生长性能、表观消化率和热应激肉牛的血清参数。四十头肉牛随机分为四组。对照组提供基础饮食，而CHM、γ-氨基丁酸（GABA）和CHM+GABA组分别在基础饮食中提供CHM、RP-GABA和CHM加RP-GABA。我们的结果表明，CHM + GABA 提高表观消化率，包括粗蛋白、Ca、P、粗脂肪 (CF) ( p  < .01) 和中性洗涤纤维 (NDF) ( p  < .05)，但与CHM 和 GABA 组的 CF 和 NDF 消化率（p  > .05)。更重要的是，CHM、GABA 和 CHM + GABA 组的平均日增重 (ADG) 得到改善，而平均日采食量 (ADFI) 仅在 CHM + GABA 组显着增加 ( p < .05 )  。同时，CHM + GABA 在血清激素、免疫球蛋白、离子含量和血液炎症细胞因子方面显示出比其他治疗组和对照组更显着的积极作用。这些结果表明，CHM 和 GABA 均能有效缓解热应激反应，联合用药在抗热应激方面具有协同作用。