The present study was conducted to investigate the influence of fermented Broussonetia Papyrifera (FBP) on growth performance, intestinal antioxidant capacity, inflammation and microbiota of grass carp. Fish (initial weight: 50.0 ± 0.5 g) were fed diets with 0 (control diet), 5 % (FBP5), 10 % (FBP10), 15 % (FBP15) and 20 % (FBP20) of FBP supplementation respectively for 8 weeks. The results showed that FBP5 group significantly decreased FCR of grass carp (P < 0.05). Besides, FBP supplementation significantly decreased intestine Cu/Zn SOD activity (P < 0.05), as well as significantly elevated mRNA expression level of kelch-like-ECH-associated protein 1 (keap1) and depressed mRNA expression level of NF-E2-related factor 2 (nrf2), superoxide dismutase 1 (sod1) and catalase (cat) (P < 0.05). The content of malondialdehyde (MDA) increased significantly in the FBP20 group compared to the control diet (P < 0.05). The expression level of interleukin-8 (il-8) and interferon γ (ifnγ) downregulated with increased dietary FBP, and significant difference was found in FBP20 group (P < 0.05). In addition, when the supplementation of FBP was no more than 15 %, the abundance of Firmicutes and Fusobacteria increased significantly, while the abundance of Actinobacteria and Cyanobacteria decreased significantly in intestine of grass carp (P < 0.05). Compared to the control diet, the richness and diversity of intestinal microbiota of grass carp decreased significantly in FBP20 group (P < 0.05). According to the second order polynomial regression equation analysis of SGR and FCR, the optimal additional level of FBP was estimated to be 4.58 % and 5.28 %, respectively. The recommended maximum addition of FBP in diet of grass carp was up to 15 % according to the results of intestinal microbiota.

本研究旨在研究发酵的布鲁氏假单胞菌（FBP）对草鱼生长性能，肠道抗氧化能力，炎症和微生物群的影响。鱼（初始体重：50.0±0.5 g）分别饲喂0（对照日粮），5％（FBP5），10％（FBP10），15％（FBP15）和20％（FBP20）的FBP饲料，持续8周。结果表明，FBP5组显着降低草鱼的FCR（P <0.05）。此外，添加FBP显着降低了肠道Cu / Zn SOD活性（P <0.05），并显着提高了kelch-like-ECH相关蛋白1（keap1）的mRNA表达水平，并降低了NF-E2相关的mRNA表达水平。因子2（nrf2），超氧化物歧化酶1（sod1）和过氧化氢酶（cat）（P <0.05）。与对照饮食相比，FBP20组的丙二醛（MDA）含量显着增加（P <0.05）。日粮FBP升高下调白细胞介素8（il-8）和干扰素γ（ifnγ）的表达水平，FBP20组差异有统计学意义（P <0.05）。此外，当FBP的添加量不超过15％时，Firmicutes和Fusobacteria的丰度显着增加，而放线菌和Cyanobacteria的丰度则增加。草鱼肠道中的蛋白质含量显着下降（P <0.05）。与对照饮食相比，FBP20组草鱼肠道菌群的丰富度和多样性显着降低（P <0.05）。根据SGR和FCR的二阶多项式回归方程分析，FBP的最佳附加水平分别估计为4.58％和5.28％。根据肠道菌群的结果，建议在草鱼日粮中添加的FBP最高可达15％。