本试验旨在探讨不同比例玉屏风多糖对草鱼肠黏膜形态结构及主要免疫与吸收相关基因表达的影响。试验选择750尾平均体重为（74.50±2.50）g的健康草鱼，随机分为5组，每组6个重复，每个重复25尾。对照组（Ⅰ组）投喂基础饲料，试验组（Ⅱ~Ⅴ组）投喂在基础饲料基础上分别添加0.8、1.2、1.6、2.0 g/kg玉屏风多糖的试验饲料。预试期7 d，正试期28 d。结果表明：1）与对照组相比，在试验第14天时，Ⅴ组的隐窝深度显著降低（P<0.05），而绒腺比则显著提高（P<0.05）。2）对照组相比，在试验第7天时，Ⅲ和Ⅳ组头肾中白介素-2（IL-2）mRNA相对表达量显著或极显著提高（P<0.05或P<0.01），Ⅱ、Ⅲ、Ⅳ和Ⅴ组头肾中干扰素γ（IFN-γ）mRNA相对表达量均极显著提高（P<0.01），Ⅲ、Ⅳ和Ⅴ组肠道中钠葡萄糖转运蛋白1（SGLT-1）和葡萄糖转运蛋白2（GLUT-2）mRNA相对表达量显著或极显著提高（P<0.05或P<0.01））。3）与对照组相比，在试验第14天时，Ⅳ和Ⅴ组头肾中IL-2 mRNA相对表达量极显著提高（P<0.01），Ⅱ、Ⅲ、Ⅳ和Ⅴ组头肾中IFN-γ mRNA相对表达量显著或极显著提高（P<0.05或P<0.01），Ⅲ、Ⅳ和Ⅴ组肠道中SGLT-1和GLUT-2 mRNA相对表达量极显著提高（P<0.01）。4）与对照组相比，在试验第21天时，Ⅳ组头肾中IL-2 mRNA相对表达量显著提高（P<0.05），Ⅱ、Ⅲ、Ⅳ和Ⅴ组头肾中IFN-γ mRNA相对表达量极显著提高（P<0.01），Ⅱ、Ⅲ、Ⅳ和Ⅴ组肠道中SGLT-1和GLUT-2 mRNA相对表达量显著或极显著提高（P<0.05或P<0.01）。5）与对照组相比，在试验第28天时，Ⅳ和Ⅴ组头肾中IL-2 mRNA相对表达量极显著提高（P<0.01），Ⅲ、Ⅳ和Ⅴ组头肾中IFN-γ mRNA相对表达量显著或极显著提高（P<0.05或P<0.01），Ⅱ、Ⅲ、Ⅳ和Ⅴ组肠道中SGLT-1 mRNA相对表达量显著或极显著提高（P<0.05或P<0.01）。综上所述，在草鱼饲料中添加一定量的玉屏风多糖能够改善肠黏膜形态结构，促进肠道中SGLT-1和GLUT-2基因的表达，调控头肾中IL-2和IFN-γ基因的表达，从而提高肠道吸收功能、增强机体免疫力。从节约饲养成本出发，草鱼饲料中玉屏风多糖最适添加量为1.6 g/kg。

This experiment was designed to investigate the effects of Yupingfeng polysaccharide on morphology of intestinal mucosa and expression of main immune and absorption genes of grass carp (Ctenopharyngodon idellus). A total of 750 healthy grass carp with an average body weight of (74.50±2.50) g were randomly assigned to 5 groups with 3 replicates per group and 50 fish per replicate. The first group (group Ⅰ) was the control group and fed a basal diet, and the remaining four groups (groups Ⅱ, Ⅲ, Ⅳ and Ⅴ) were experimental groups and fed experimental diets supplementing 0.8, 1.2, 1.6 and 2.0 g/kg Yupingfeng polysaccharide based on the basal diet, respectively. The pre-trial period was 7 days, and the formal trial period was 28 days. The results showed as follows:1) feeding for 14 days, the crypt depth of group Ⅴ was significantly lower than that of control group (P<0.05), and the villus height/crypt depth of group Ⅴ was significantly higher than that of control group (P<0.05). 2) On the trial day 7, compared with the control group, the relative expression level of interleukin-2 (IL-2) mRNA in head-kidney of groups Ⅲ and Ⅳ was significantly or extremely significantly increased (P<0.05 or P<0.01), the relative expression level of interferon γ (IFN-γ) mRNA in head-kidney of groups Ⅱ, Ⅲ, Ⅳ and Ⅴ was extremely significantly increased (P<0.01), and the relative expression levels of sodium glucose transporter 1 (SGLT-1) and glucose transport protein 2 (GLUT-2) mRNA in intestine of groups Ⅲ, Ⅳ and Ⅴ were significantly or extremely significantly increased (P<0.05 or P<0.01). 3) On the trial day 14, compared with the control group, the relative expression level of IL-2 mRNA in head-kidney of groups Ⅳ and Ⅴ was extremely significantly increased (P<0.01), the relative expression level of IFN-γ mRNA in head-kidney of groups Ⅱ, Ⅲ, Ⅳ and Ⅴ was significantly or extremely significantly increased (P<0.05 or P<0.01), and the relative expression levels of SGLT-1 and GLUT-2 mRNA in intestine of groups Ⅲ, Ⅳ and Ⅴ were extremely significantly increased (P<0.01). 4) On the trial day 21, compared with the control group, the relative expression level of IL-2 mRNA in head-kidney of group Ⅳ was significantly increased (P<0.05), the relative expression level of IFN-γ mRNA in head-kidney of groups Ⅱ, Ⅲ, Ⅳ and Ⅴ was extremely significantly increased (P<0.01), and the relative expression levels of SGLT-1 and GLUT-2 mRNA in intestine of groups Ⅱ, Ⅲ, Ⅳ and Ⅴ were significantly or extremely significantly increased (P<0.05 or P<0.01). 5) On the trial day 28, compared with the control group, the relative expression level of IL-2 mRNA in head-kidney of groups Ⅳ and Ⅴ was extremely significantly increased (P<0.01), the relative expression level of IFN-γ mRNA in head-kidney of groups Ⅲ, Ⅳ and Ⅴ was significantly or extremely significantly increased (P<0.05 or P<0.01), and the relative expression levels of SGLT-1 and GLUT-2 mRNA in intestine of groups Ⅱ, Ⅲ, Ⅳ and Ⅴ were significantly or extremely significantly increased (P<0.05 or P<0.01). On the whole, supplementing a certain amount of Yupingfeng polysaccharide in the diet can improve the morphology of intestinal mucosa, promote the expression of SGLT-1 and GLUT-2 genes in intestine, regulate the expression of IL-2 and IFN-γ genes in head-kidney, and then improve the intestinal absorption function and immunity of grass carp. In consideration of saving cost, the optimum supplemental level of Yupingfeng polysaccharide in the diet of grass carp is 1.6 g/kg.