This study examined the effect of konjac glucomannan (KGM) supplementation in diets with different lipid levels on growth, antioxidant capacity, hepatic lipid metabolism and inflammatory response in juvenile pompano (Trachinotus ovatus). Triplicate groups of fish (12.07 ± 0.21 g) were fed eight experimental diets containing two lipid levels of 9% (basal-fat diet, BFD) and 18% (high-fat diet, HFD), and four levels of KGM (0, 0.5, 1 and 2%) for 60 days. Pompano fed HFD exhibited markedly lower growth and feed efficiency than fish fed BFD, and KGM supplementation, particularly at 1% inclusion, significantly improved growth performance and feed efficiency in fish fed both BFD and HFD. In addition, Pompano fed HFD showed higher whole-body lipid and lower protein contents than fish fed BFD. Irrespective of dietary lipid level, whole body, dorsal and ventral muscle were reduced by dietary KGM supplementation up to 1% while the opposite was found for whole body protein content. Dietary KGM also significantly reduced the HSI, liver lipid contents, as well as lipid droplets in the liver. Supplementation of KGM to both BFD and HFD significantly reduced serum total cholesterol, triglyceride, low-density lipoprotein cholesterol and free fatty acids levels. Furthermore, irrespective of dietary lipid level, increasing dietary KGM supplementation enhanced serum IgM level, lysozyme and alkaline phosphatase activities, and reduced serum alanine aminotransferase and aspartate aminotransferase activities. Dietary KGM also increased liver total antioxidant capacity, superoxide dismutase and catalase activities, and decreased malondialdehyde concentration in fish fed both HFD and BFD. Dietary KGM significantly increased serum glutathione peroxidase, superoxide dismutase and catalase activities and reduced malondialdehyde concentrations in fish fed BFD, and enhanced serum total antioxidant capacity and glutathione peroxidase activity in fish fed HFD. Supplementation of KGM increased the expression of genes associated with lipid catabolism (pparα, cpt1, hsl) and lipid transport (fabp1, apoB100 and cd36), and decreased the expression of lipid anabolism related genes (srebp1, pparγ, fas and acc). Moreover, the expression of pro-inflammatory cytokines including tumor necrosis factor α and interleukin-8 were down-regulated, while expression of the anti-inflammatory cytokine transforming growth factor β1 was increased by KGM supplementation. In conclusion, supplementation of KGM at 1% of diet improved growth, feed efficiency, antioxidant capacity, hepatic lipid metabolism and inflammatory responses in juvenile pompano, and can mitigate excessive deposition of lipid in tissues of farmed fish.

本研究检查了在不同脂质水平的饮食中添加魔芋葡甘露聚糖 (KGM) 对幼年鲳 ( Trachinotus ovatus)生长、抗氧化能力、肝脏脂质代谢和炎症反应的影响。）。三组鱼 (12.07 ± 0.21 g) 被喂食八种实验饮食，其中含有两种脂质水平 9%（基础脂肪饮食，BFD）和 18%（高脂肪饮食，HFD），以及四种水平的 KGM（0, 0.5、1 和 2%），持续 60 天。喂食 HFD 的 Pompano 的生长和饲料效率明显低于喂食 BFD 的鱼，而 KGM 补充剂，特别是添加 1% 时，显着提高了 BFD 和 HFD 饲料鱼的生长性能和饲料效率。此外，与喂食 BFD 的鱼相比，喂食 HFD 的 Pompano 显示出更高的全身脂质和较低的蛋白质含量。不考虑膳食脂质水平，通过膳食 KGM 补充剂减少高达 1% 的全身、背侧和腹侧肌肉，而全身蛋白质含量则相反。膳食 KGM 还显着降低了 HSI、肝脏脂质含量以及肝脏中的脂滴。在 BFD 和 HFD 中补充 KGM 显着降低了血清总胆固醇、甘油三酯、低密度脂蛋白胆固醇和游离脂肪酸水平。此外，无论膳食脂质水平如何，增加膳食 KGM 补充剂可提高血清 IgM 水平、溶菌酶和碱性磷酸酶活性，并降低血清丙氨酸氨基转移酶和天冬氨酸氨基转移酶活性。膳食 KGM 还增加了肝脏总抗氧化能力、超氧化物歧化酶和过氧化氢酶活性，并降低了喂食 HFD 和 BFD 的鱼的丙二醛浓度。日粮 KGM 显着增加了血清谷胱甘肽过氧化物酶、超氧化物歧化酶和过氧化氢酶的活性，并降低了饲喂 BFD 的鱼的丙二醛浓度，和增强喂食 HFD 的鱼的血清总抗氧化能力和谷胱甘肽过氧化物酶活性。补充 KGM 增加了与脂质分解代谢相关的基因的表达。PPARα，CPT1，HSL）和脂质转运（FABP1，载脂蛋白B100和CD36），和降低的脂质合成相关的基因（表达SREBP1，PPARγ，FAS和ACC）。此外，包括肿瘤坏死因子 α 和白细胞介素 8 在内的促炎细胞因子的表达被下调，而抗炎细胞因子转化生长因子 β1 的表达因 KGM 补充而增加。总之，在日粮中添加 1% 的 KGM 可以改善鲳鱼幼鱼的生长、饲料效率、抗氧化能力、肝脏脂质代谢和炎症反应，并可以减轻养殖鱼类组织中脂质的过度沉积。