Abstract：
The largemouth bass has become one of the economically fish in China, according to the latest China Fishery Statistical Yearbook. The farming scale is constantly increasing. Salidroside has been found in past studies to have oxidative stress reducing and immune boosting properties. In this study, the addition of six different levels of salidroside supplements were 0、40、80、120、160 and 200 mg/kg. A 56-day feeding trial was conducted to investigate the effects of salidroside on the intestinal health, immune parameters and intestinal microbiota composition of largemouth bass. Dietary addition of salidroside significantly affected the Keap-1β/Nrf-2 pathway as well as significantly increased antioxidant enzyme activities resulting in a significant increase in antioxidant capacity of largemouth bass. Dietary SLR significantly reduced feed coefficients. The genes related to tight junction proteins (Occludin, ZO-1, Claudin-4, Claudin-5) were found to be significantly upregulated in the diet supplemented with salidroside, indicating that salidroside can improve the intestinal barrier function (p < 0.05). The dietary administration of salidroside was found to significantly reduce the transcription levels of intestinal tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) (p < 0.05). Furthermore, salidroside was observed to reduce the transcription levels of intestinal apoptosis factor Bcl-2 associated death promoter (BAD) and recombinant Tumor Protein p53 (P53) (p < 0.05). Concomitantly, the beneficial bacteria, Fusobacteriota and Cetobacterium, was significantly increased in the SLR12 group, while that of pathogenic bacteria, Proteobacteria, was significantly decreased (p < 0.05). In conclusion, the medium-sized largemouth bass optimal dosage of salidroside in the diet is 120mg/kg-1.
摘要：
大嘴鲈鱼已成为中国经济鱼类之一，根据最新的《中国渔业统计年鉴》。养殖规模不断扩大。在过去的研究中发现红景天苷具有减少氧化应激和增强免疫的特性。在这项研究中,添加6种不同水平的红景天苷补充剂分别为0、40、80、120、160和200mgkg-1。进行了为期56天的喂养试验，以研究红景天苷对肠道健康的影响，大嘴鲈鱼的免疫参数和肠道菌群组成。日粮添加红景天苷显著影响Keap-1β/Nrf-2途径，并显著增加抗氧化酶活性，导致大嘴鲈鱼抗氧化能力显著提高。日粮SLR显著降低饲料系数。与紧密连接蛋白相关的基因(Occludin，发现ZO-1，Claudin-4，Claudin-5）在补充红景天苷的饮食中显着上调，说明红景天苷能改善肠屏障功能(p<0.05)。饮食中红景天苷可显著降低肠道肿瘤坏死因子-α(TNF-α)和白细胞介素-1β(IL-1β)的转录水平(p<0.05)。此外，观察到红景天苷可降低肠道凋亡因子Bcl-2相关死亡启动子（BAD）和重组肿瘤蛋白p53（P53）的转录水平（p<0.05）。同时，有益菌,梭菌和细菌，在SLR12组中显著增加，而致病菌，变形杆菌,显著降低(p<0.05)。总之,中型大口鲈鱼在日粮中的最佳用量为120mg/kg-1。
