Abstract: The purpose of this experiment was to explore the changes in physiological indices， serum biochemical indices and immune function of Hu sheep with different heat tolerance，and to provide reference for analyzing the heat tolerance mechanism of Hu sheep and formulating strategies to alleviate heat stress of sheep. From July 1 to August 20，under the condition of an average THI（Temperature⁃Humidity Index）of 85.5，a total of 811 multiparous，non⁃pregnant ewes with consistent parity（all having given birth twice），good health status，and identical feeding management were selected and raised collectively in a single shed. Indicators such as respiratory rate，rectal temperature，and heart rate were measured. Using principal component analysis and membership function analysis，heat⁃resistant（HR）Hu sheep（n=30）and heat⁃sensitive（HS）Hu sheep （n=30）were identified. The results showed that the respiratory frequency，rectal temperature and heart rate of Hu sheep in HS group were significantly higher than those in HR group（P<0.01）. WBC and HGB in the blood routine of Hu sheep in HR group were significantly higher than those in HS group（P<0.01），and LYM was significantly higher than that in HS group（P<0.05）. The contents of serum HSP70 and HSP90 in HR group were significantly higher than those in HS group（P<0.01）. The contents of T3， T4 and COR in HR group were significantly higher than those in HS group（P<0.01）. The concentrations of TNF⁃α，IL⁃1β and IL⁃6 in HR group were also significantly higher than those in HS group（P<0.01）. In conclusion，compared with HS Hu sheep，HR Hu sheep exhibit stronger heat stress resistance and immune capacity.

Key words: Heat stress, Heat resistance, Hu sheep, Physiological indicators, Serum biochemical indexes, Immune function

摘要： 该试验旨在探究不同耐热性湖羊生理指标、血清生化指标及免疫功能的变化规律， 为解析湖羊耐热性机制和制定缓解绵羊热应激策略提供参考依据。在夏季7月1日－8月20日 平均温热指数（temperature?humidity index, THI）在85.5的条件下，试验共选取811只胎次一致 （均产过2胎）、健康状况良好且采用相同饲养管理的经产空怀母羊于一幢羊舍集中饲养，检测 呼吸频率、直肠温度和心率等指标，采用主成分和隶属函数分析法筛选出耐热（Heat resis? tance，HR）湖羊（n=30）和热敏感（Heat stress，HS）湖羊（n=30）。结果显示：HS组湖羊的呼吸频 率、直肠温度和心率显著高于HR组（P<0.01）；HR组湖羊血常规中白细胞总数（WBC）和血红蛋 白浓度（HGB）极显著高于HS组（P<0.01），淋巴细胞数（LYM）显著高于HS组（P<0.05）。HR组 血清热休克蛋白70（HSP70）、热休克蛋白HSP90（HSP90）含量极显著高于HS组（P<0.01）；HR组 三碘甲状腺原氨酸（T3）、甲状腺素（T4）、皮质醇（COR）含量极显著高于HS组（P<0.01）；HR组免 疫炎症因子肿瘤坏死因子?α（TNF?α）、白细胞介素?1β（IL?1β）和白细胞介素?6（IL?6）的浓度也均 极显著高于HS组（P<0.01）。综上所述，与HS湖羊相比，HR湖羊的抗热应激和免疫能力更强。

关键词: 热应激, 耐热性, 湖羊, 生理指标, 血清生化指标, 免疫功能