An 8-week feeding experiment was carried out to explore the effects of dietary n-3/n-6 polyunsaturated fatty acid (PUFA) ratio on growth performance, lipid metabolism, hepatic antioxidant status, and gut flora of spotted seabass (Lateolabrax maculatus). Six experimental diets were formulated to contain different levels of two purified oil sources including docosahexaenoic and eicosapentaenoic acids enriched oil (n-3) and linoleic acid-enriched oil (n-6) leading to n-3/n-6 PUFA ratios of 0.04, 0.35, 0.66, 1.35, 2.45 and 16.17. Each diet was fed to triplicate groups of juvenile L. maculatus (11.06 ± 0.20 g, 30 fish/tank). Final body weight (FBW), weight gain (WG), specific growth rates (SGR), protein efficiency ratio (PER) and feed utilization efficiency increased as n-3/n-6 PUFA ratio increased up to a certain level, and then decreased thereafter. Fish fed the diet with n-3/n-6 PUFA ratio of 0.66 exhibited the highest FBW, WG, SGR and PER and the lowest feed conversion ratio. Lower n-3/n-6 PUFA ratios induced up-regulated expression of lipid synthesis-related genes (fas, acc2 and srebp-1c) and down-regulated expression of lipolysis related genes (atgl, pparα, cpt-1 and aox). Higher expression of lipolysis-related genes (atgl, pparα and cpt-1) was recorded at moderate n-3/n-6 PUFA ratios (0.66 to 1.35). Moreover, inappropriate n-3/n-6 PUFA ratios triggered up-regulation of pro-inflammatory genes (il-6 and tnf-α) and down-regulation of anti-inflammatory genes (il-4 and il-10) in the intestine. The diet with n-3/n-6 PUFA ratio of 0.66 inhibited intestine inflammation, improved intestinal flora richness, increased the abundance of beneficial bacteria such as Lactobacillus, Alloprevotella and Ruminococcus, and reduced the abundance of harmful bacteria including Escherichia-Shigella and Enterococcus. In summary, it could be suggested that a dietary n-3/n-6 PUFA ratio of 0.66 can improve growth performance and feed utilization in L. maculatus, as is deemed to be mediated through regulation of lipid metabolism and intestinal flora.

一项为期 8 周的饲养实验旨在探讨日粮 n-3/n-6 多不饱和脂肪酸 (PUFA) 比例对斑点鲈鱼 (Lateolabrax maculatus) 生长性能、脂质代谢、肝脏抗氧化状态和肠道菌群的影响. 六种实验饮食被配制为包含不同水平的两种纯化油源，包括富含二十二碳六烯酸和二十碳五烯酸的油 (n-3) 和富含亚油酸的油 (n-6)，导致 n-3/n-6 PUFA 比率为 0.04 , 0.35, 0.66, 1.35, 2.45 和 16.17。将每种饮食喂养成三组幼年L. maculatus（11.06 ± 0.20 克，30 条鱼/缸）。最终体重（FBW）、增重（WG）、比生长率（SGR）、蛋白质效率比（PER）和饲料利用效率随着n-3/n-6 PUFA比例增加到一定水平而增加，然后之后有所下降。喂食 n-3/n-6 PUFA 比例为 0.66 的鱼表现出最高的 FBW、WG、SGR 和 PER 以及最低的饲料转化率。较低的 n-3/n-6 PUFA 比率诱导脂质合成相关基因（fas、acc2和srebp-1c）的表达上调和脂肪分解相关基因（atgl、pparα、cpt-1和aox）的表达下调. 脂肪分解相关基因（atgl, pparα和cpt-1 ) 以中等 n-3/n-6 PUFA 比率（0.66 至 1.35）记录。此外，不适当的 n-3/n-6 PUFA 比例会引发促炎基因（il-6和tnf-α）的上调和抗炎基因（il-4和il-10）的下调。肠。n-3/n-6 PUFA比例为0.66的日粮可抑制肠道炎症，改善肠道菌群丰富度，增加乳酸菌、异普雷沃氏菌、瘤胃球菌等有益菌丰度，降低大肠杆菌、志贺氏菌、肠球菌等有害菌丰度. 总之，可以表明 0.66 的日粮 n-3/n-6 多不饱和脂肪酸比率可以提高斑斑乳鱼的生长性能和饲料利用率，这被认为是通过调节脂质代谢和肠道菌群介导的。