中文摘要：

观察热应激对猪肠道黏膜结构的损伤作用，以揭示热应激降低猪增重率的机理。12头小型猪随机分成热应激组和常温对照组两组。人工气候室内，热应激组模拟夏季炎热气候，气温从26—39℃24h循环变温，在39℃时维持4h；常温对照组在24℃下饲养。试验持续10d，分别于热应激前、热应激第5d和热应激结束时称重，计算各组的体重增长率。热应激10d后39℃高温持续期结束时剖杀试验猪，取其十二指肠、空肠及回肠进行固定、石蜡切片、染色，染色和扫描电镜H．E．染色切片观察肠黏膜形态变化，并检测肠绒毛长度、宽度、隐窝深度，绒毛长度／隐窝深度；PAS染色切片检测肠黏膜上皮内杯状细胞数量的变化；用Gomori氏改良法染色切片观测肠黏膜碱性磷酸酶活性的变化。与对照组相比较，热应激组猪的体重增长率显著下降（P〈0．05）；热应激后猪肠黏膜结构严重损伤；各段肠的绒毛长度、宽度、隐窝深度，绒毛长度／隐窝深度均出现不同程度的降低，其中回肠绒毛长度减少较为显著（P〈0．05），各肠段绒毛宽度的减少均差异显著（P〈0．05）；肠黏膜上皮内杯状细胞数量增多，其中回肠差异显著（P〈0．05）；热应激组猪的肠黏膜上皮细胞表面的碱性磷酸酶活性明显降低。热应激可引起猪肠道黏膜结构严重损伤，以致小肠的消化吸收功能严重受阻，这是造成猪热应激掉膘减重的主要机制之一。

英文摘要：

Twelve healthy three-month-old pigs were divided into two groups at random , heat stress group and control group. The two groups were put into different AGCs, one of which simulated high temperature in summer （ the temperature changed from 26℃ to 39℃and lasted four hours when 39℃ ） , the other always keep 24℃. The experiment lasted ten days and in the 5th and 10th day, all pig＇s body weights were obtained and average weight gain ratios were calculated. In the 10th day , all pigs of each group were sacrificed soon after 39℃ heat stress and their duodenum, jejunum and ileum were fixed by a solution containing 4% paraformaldehyde, 0.1% glutaraldehyde, and 0.2% picric acid in 0.1 mol phosphate buffer. To observe the changes of structure of duodenum through micro-telescope examination by the way of H. E. staining and scanning electron micrograph. To observe villus length,crypt depth, V/C and villus width of duodenum, jejunum and ileum through micro-telescope examination by the way of H. E. staining. To observe the number of goblet cells through through micro-telescope examination by the way of PAS. staining. Besides, the activity of AKP was tested through the Gomori staining. The results showed that duodenum structure of heat stress group was destroyed seriously. The villus length, crypt depth, V/C and villus width of duodenum, jejunum and ileum of heat stress group were lower than those of control group, and that, the lenth of jejunum and the width of duodenum, jejunum and ileum changed dramatically（P 〈 0.05 ）. Compared with the control group, the number of goblet cells in ileum of heat stress group increased significantly（P 〈0.05）. Tthe activity of AKP in the heat stress group turned out to be remarkably decreased. The data presented indicated that heat stress restrained assimilation of pig＇s intestines, and that was one perspective that heat stress effects performance in pig.