本试验旨在研究饲料中添加谷氨酰胺二肽对草鱼幼鱼生长、血清生化、免疫指标及肠道组织结构的影响。选取健康、平均体重为（7.16±0.10）g的草鱼幼鱼750尾，随机分为5组，每组3个重复，每个重复50尾，分别饲喂含0（对照组）、0.25%、0.50%、0.75%、1.00%谷氨酰胺二肽的试验饲料。养殖试验持续8周。结果表明：1）与对照组相比，饲料中添加谷氨酰胺二肽显著提高了草鱼幼鱼增重率和蛋白质效率（P<0.05），显著降低了饲料系数（P<0.05）；且0.25%、0.50%组肠道脂肪酶和胰蛋白酶活性显著高于对照组（P<0.05）。2）与对照组相比，0.75%组血清葡萄糖含量显著升高（P<0.05），饲料中添加谷氨酰胺二肽显著提高了血清尿素氮含量（P<0.05）。饲料中添加谷氨酰胺二肽有使血清甘油三酯和胆固醇含量下降的趋势，其中0.50%组血清胆固醇含量显著低于对照组（P<0.05），各添加组血清甘油三酯含量均显著低于对照组（P<0.05）。谷氨酰胺二肽添加量超过0.50%使得血清谷草转氨酶和谷丙转氨酶活性显著升高（P<0.05）。3）与对照组相比，0.50%组血清溶菌酶活性显著上升（P<0.05）。0.75%、1.00%组血清补体4（C4）含量显著降低（P<0.05），皮质醇含量显著升高（P<0.05）。各添加组血清谷胱甘肽含量、总抗氧化能力显著升高（P<0.05）。4）与对照组相比，0.50%组肠道隐窝深度显著降低（P<0.05），0.75%、1.00%组肠道黏膜厚度显著增加（P<0.05），0.50%和1.00%组杯状细胞数量显著增加（P<0.05）。综上所述，饲料中添加0.50%谷氨酰胺二肽能够促进草鱼幼鱼营养物质代谢、免疫以及肠道发育，进而促进生长。

The aim of this experiment was to study the effects of glutamine dipeptide (Gly-Gln) on the growth, serum biochemistry, immunity indexes and intestinal morphology of juvenile grass carp. A total of 750 fish with an average body weight of (7.16±0.10) g were selected and divided into 5 groups with 3 replicates per group and 50 fish per replicate. Fish were fed diets containing 0 (control group) and 0.25%, 0.50%, 0.75% and 1.00% glutamine dipeptide, respectively. The feeding test lasted for 8 weeks. The results showed as follows:1) compared with the control group, the weight gain rate and protein efficiency of juvenile grass carp increased significantly (P<0.05) and the feed coefficient decreased significantly (P<0.05) in the glutamine dipeptide supplementation groups. Dietary supplementation of 0.25% and 0.50% glutamine dipeptide significantly increased intestinal lipase and trypsin activities (P<0.05). 2) Compared with the control group, the serum glucose content in 0.75% group significantly increased (P<0.05), and the serum urea nitrogen content in each glutamine dipeptide supplementation group significantly increased (P<0.05). The addition of glutamine dipeptide in the feed made the serum triglyceride and cholesterol contents decrease, and the cholesterol content in 0.50% group significantly decreased compared with the control group (P<0.05), serum triglyceride content in each supplementation group significantly decreased compared with the control group (P<0.05). The activities of glutamic oxalacetic transaminase and alanine aminotransferase significantly increased when the dosage was more than 0.50% (P<0.05). 3) Compared with the control group, the serum lysozyme activity in 0.50% group increased significantly (P<0.05). Serum complement 4 content decreased significantly in 0.75% and 1.00% groups (P<0.05), while the cortisol content increased significantly (P<0.05). The serum glutathione content and total antioxidant capacity significantly increased in each supplementation group (P<0.05). 4) Compared with the control group, the intestinal crypt depth significantly reduced in 0.5% group (P<0.05), the intestinal mucosal thickness significantly increased in the 0.75% and 1.00% groups (P<0.05), and the number of goblet cells significantly increased in the 0.50% and 1.00% groups (P<0.05). In summary, the addition of 0.50% glutamine dipeptide to the feed can promote nutrient metabolism, immunity and intestinal development of grass carp juveniles, thereby promoting growth.