This study was conducted to investigate the effects of diet 7.5 g/kg α-ketoglutarate (AKG) on the growth performance, antioxidant defense system, digestive enzymes, and immune response of grass carp (Ctenopharyngodon idellus). A total of 400 grass carp with an average body weight 10.81 ± 0.68 g was randomly allocated into 2 groups with 4 replicates of 50 fish respectively. The experiment was conducted in net cages (1.5 m × 1.5 m × 1.5 m) suspended in an indoor cement pool. Fish were fed a basic diet containing either 0 (control) or 7.5 g/kg AKG (supplemented diet). The experiment lasted for 8 weeks (56 days). Results indicated that compared with the control group, the final weight (FW), weight gain rate (WGR), specific growth rate (SGR), and protein efficiency ratio (PER) in the AKG group were increased significantly (P < 0.05). However, the feed conversion ratio (FCR) was decreased significantly (P < 0.05). The 7.5 g/kg AKG supplementation significantly increased the activities of glutamine synthetase (GS), glutathione peroxidase (GSH-Px), catalase (CAT), total superoxide dismutase (T-SOD), and hexokinase (HK), as well as the concentrations of glutathione (GSH), total antioxidant capacity (T-AOC), and complement 3 (C3) in blood (P < 0.05), while significantly decreased the concentrations of malondialdehyde (MDA) and hemoglobin (Hb) (P < 0.05). The GS activity and GSH concentration in hepatopancreas were increased significantly (P < 0.05), whereas the glycogen concentration in hepatopancreas, and the glycogen concentration and GS activity in the muscle were significantly decreased (P < 0.05). In addition, 7.5 g/kg AKG supplementation significantly increased the concentration of GSH and the activities of amylase, protease, and lipase in fore-gut, alkaline phosphates (ALP) in the mid-gut, and Na-ATP and Ca-ATP in the gill (P < 0.05), as well as γ-glutamyl transpeptidase (γ-GT) both in fore-gut and mid-gut (P < 0.05), whereas the activity of acid phosphatase (ACP) in the mid-gut was decreased significantly (P < 0.05). In conclusion, diet 7.5 g/kg AKG supplementation in grass carp may improve the growth performance and immune response and play crucial roles in regulating the activities of GS, antioxidant defense system, and digestive enzymes.

本研究旨在研究日粮7.5 g / kgα-酮戊二酸（AKG）对草鱼（Ctenopharyngodon idellus）的生长性能，抗氧化防御系统，消化酶和免疫反应的影响。）。将平均体重为10.81±0.68 g的400条草鱼随机分为2组，每组4条重复，每条50条鱼。实验是在悬挂在室内水泥池中的网箱（1.5 m×1.5 m×1.5 m）中进行的。鱼的基本日粮饲喂0（对照）或7.5 g / kg AKG（补充日粮）。实验持续了8周（56天）。结果表明，与对照组相比，AKG组的最终体重（FW），体重增加率（WGR），比生长率（SGR）和蛋白质效率比（PER）显着增加（P  <0.05）。但是，饲料转化率（FCR）明显降低（P <0.05）。补充7.5 g / kg AKG可以显着增加谷氨酰胺合成酶（GS），谷胱甘肽过氧化物酶（GSH-Px），过氧化氢酶（CAT），总超氧化物歧化酶（T-SOD）和己糖激酶（HK）的活性。血液中谷胱甘肽（GSH），总抗氧化能力（T-AOC）和补体3（C3）的浓度（P  <0.05），而丙二醛（MDA）和血红蛋白（Hb）的浓度显着降低（P  <0.05） 。肝胰腺中的GS活性和GSH浓度显着增加（P  <0.05），肝胰腺中的糖原浓度以及肌肉中的糖原浓度和GS活性显着降低（P <0.05）。此外，补充7.5 g / kg AKG可以显着提高前肠中GSH的浓度以及淀粉酶，蛋白酶和脂肪酶的活性，中肠中碱性磷酸酶（ALP）的含量以及Na-ATP和Ca-ATP的含量。 前肠和中肠的g（P <0.05）以及γ-谷氨酰转肽酶（γ-GT）（P  <0.05），而中肠的酸性磷酸酶（ACP）活性为显着下降（P  <0.05）。总之，在草鱼中添加7.5 g / kg AKG的日粮可改善其生长性能和免疫反应，并在调节GS活性，抗氧化防御系统和消化酶方面发挥关键作用。