The present study was conducted to explore the influence of dietary carbohydrate on antioxidant capacity and non-specific immunity of hybrid grouper, which would contribute to determine the tolerable dietary carbohydrate content. Seven diets with grade levels of carbohydrate (5.27, 8.95, 11.49, 14.37, 17.78, 20.82 and 23.65%) were fed to triplicate groups of fish for 10 weeks. Results showed that the inclusion of carbohydrate above 11.49% produced significant increased content of hydrogen peroxide (H₂O₂) in liver and malondialdehyde (MDA) in both serum and liver. The specific activity of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (Gpx) and total antioxidative capacity (T-AOC) were significantly elevated with the increase of dietary carbohydrate from 8.95 to 23.65%, which may be associated with the reduced hepatic soluble protein content. However, opposite variation was observed in the expression of antioxidant related genes (SOD1 and Gpx), which was partly caused by the activation of NF-E2-related factor 2 (Nrf2) and inhibition of Kelch-like-ECH-associated protein 1 (Keap1) at the transcriptional level. The immunoglobulin M (lgM) content and activity of lysozyme and CCP in serum significantly depressed when dietary carbohydrate was above 11.49%. The expression of pro-inflammatory cytokines (TNF-α, IL-1β and IL-8) was significantly increased with the increase of dietary carbohydrate from 5.27 to 8.95% and thereafter significantly reduced, which was consistent with the changed expression of toll-like receptor 2 (TLR2) and nuclear factor κΒ (NF‐κΒ). In above, high dietary carbohydrate significantly impaired the antioxidant capacity and reduced the non-specific immunity of hybrid grouper, and the tolerable dietary carbohydrate content not exceed 11.49%.

本研究旨在探讨膳食碳水化合物对杂种石斑鱼抗氧化能力和非特异性免疫的影响，这将有助于确定可耐受的膳食碳水化合物含量。将七种具有碳水化合物等级水平的饮食（5.27、8.95、11.49、14.37、17.78、20.82和23.65％）喂饲三组鱼类，持续10周。结果表明，碳水化合物含量超过11.49％时，过氧化氢（H ₂ O ₂）和丙二醛（MDA）在血清和肝脏中。随着饮食碳水化合物从8.95增至23.65％，过氧化氢酶（CAT），超氧化物歧化酶（SOD），谷胱甘肽过氧化物酶（Gpx）和总抗氧化能力（T-AOC）的比活性显着提高。降低肝脏可溶性蛋白含量。然而，在抗氧化剂相关基因（SOD1和Gpx）的表达中观察到相反的变化，部分是由NF-E2相关因子2（Nrf2）的激活和对Kelch-like-ECH相关蛋白1的抑制引起的（ Keap1）在转录水平。当日粮碳水化合物含量高于11.49％时，血清中的免疫球蛋白M（lgM）含量，溶菌酶和CCP活性显着降低。促炎细胞因子（TNF-α，IL-1β和IL-8）随饮食碳水化合物从5.27增至8.95％而显着增加，此后显着降低，这与Toll样受体2（TLR2）和核因子κΒ（NF- κΒ）。在上述情况下，高饮食碳水化合物显着削弱了杂种石斑鱼的抗氧化能力并降低了其非特异性免疫力，且可忍受的饮食碳水化合物含量不超过11​​.49％。