本试验旨在研究纤维寡糖（COS）和益生菌（PRO）对热应激肉鸡肠屏障功能的影响。将900羽21日龄罗斯（Ross）308肉鸡分为5个组：空白对照（Con）组、热应激（HS）组、益生菌（HS+PRO）组、纤维寡糖（HS+COS）组、合生素（HS+SYN，SYN=PRO+COS）组。Con组鸡舍温度22 ℃；其余各组鸡舍温度08：00—18：00为33 ℃，18：00至次日08：00为22 ℃。饲养试验期为21 d。结果表明：1）与Con组相比，HS组肉鸡平均日增重和平均日采食量分别显著降低10.65%和8.04%（P<0.05）；盲肠内容物乳酸杆菌数显著下降（P<0.05），大肠杆菌和梭菌数显著上升（P<0.05）；空肠绒毛高度和绒毛高度/隐窝深度显著降低（P<0.05）；空肠跨膜电阻（TER）值显著下降（P<0.05），荧光素异硫氰酸酯-葡聚糖（FD4）通透性显著升高（P<0.05）。2）与HS组相比，HS+PRO组和HS+COS组平均日增重、平均日采食量和料重比差异不显著（P>0.05），空肠绒毛高度和绒毛高度/隐窝深度显著升高（P<0.05），FD4通透性显著下降（P<0.05）；HS+PRO组盲肠内容物乳酸杆菌、双歧杆菌、大肠杆菌和梭菌数差异不显著（P>0.05）；HS+COS组盲肠内容物乳酸杆菌数显著上升（P<0.05），大肠杆菌和梭菌数显著下降（P<0.05）。3）与HS组相比，HS+SYN组肉鸡料重比显著降低4.21%（P<0.05）；盲肠内容物乳酸杆菌和双歧杆菌数显著上升（P<0.05），大肠杆菌和梭菌数显著下降（P<0.05）；空肠绒毛高度和绒毛高度/隐窝深度显著升高（P<0.05）；空肠TER值显著升高（P<0.05），FD4通透性显著下降（P<0.05）。结果提示，热应激使肉鸡生长性能下降，肠屏障功能受损，饲喂益生菌和纤维寡糖可改善上述变化，且两者组合添加效果优于单独添加。

This test was conducted to study the effects of cello-oligosaccharide and probiotics on intestinal barrier function of broilers in heat stress. Nine hundred 21-d-old Ross 308 broilers were randomly allocated to 5 groups: control (Con) group, heat stress (HS) group, probiotics (HS+PRO) group, cello-oligosaccharide (HS+COS) group and synbiotics (HS+SYN, SYN=PRO+COS) group. Birds were raised at 22 ℃ in Con group, and the others subjected to cyclic heat stress by exposing them to 33 ℃ from 08:00 to 18:00 and 22 ℃ from 18:00 to next day 08:00. Raising experiment period was 21 d. The results showed as follows: 1) compared with birds kept in Con group, average daily gain and average daily feed intake of birds in HS group was significantly reduced (P<0.05); the viable counts of Lactobacillus in cecal contents was significantly decreased (P<0.05), and the viable counts of Escherichia coli and Clostridium in cecal contents were significantly increased (P<0.05); jejunal villus height was significantly shorter (P<0.05), and the ratio of villus height to crypt depth was significantly lower (P<0.05); jejunal transepithelial electrical resistance (TER) value was significantly decreased (P<0.05), and the level of jejunal paracellular permeability of 4 kDa-FITC dextran (FD4) flux was significantly raised (P<0.05). 2) As compared with HS group, the average daily gain, average daily feed intake and feed to gain ratio of birds in HS+PRO and HS+COS groups were not significantly different (P>0.05); villus height and villus height to crypt depth ratio were significantly increased (P<0.05); flux of FD4 was significantly reduced (P<0.05). As compared with HS group, viable counts of Lactobacillus, Bifidobacterium, Escherichia coli and Clostridium in cecal contents in HS+PRO group were not significantly different (P>0.05), the viable counts of Lactobacillus in cecal contents was significantly increased (P<0.05), and Escherichia coli and Clostridium in cecal contents in HS+COS group were significantly decreased (P<0.05). 3) As compared with HS group, feed to gain ratio in HS+SYN group was significantly decreased by 4.21% (P<0.05); the viable counts of Lactobacillus and Bifidobacterium in cecal contents were significantly increased (P<0.05), and Escherichia coli and Clostridium in cecal contents were significantly decreased (P<0.05); villus height and villus height to crypt depth ratio were significantly increased (P<0.05); TER value was significantly increased (P<0.05) and the flux of FD4 was significantly reduced (P<0.05). These results indicate that additions of probiotics and cello-oligosaccharide are effective in partially ameliorating intestinal barrier function. The combination of probiotics and cello-oligosaccharid has better effect on ameliorating intestinal barrier function than supplementing them alone.