This study evaluated the effect of probiotics (Clostridium butyricum, Bacillus coagulans) and Chinese herb polysaccharides (Astragalus polysaccharides, APS) on growth performance, immunity, disease resistance, and intestinal microbiota of rainbow trout (Oncorhynchus mykiss). Specimens of O. mykiss (n = 360; 79.9 ± 2.2 g) were fed for 42 days with different diets containing a basal diet (control, C0), supplemented with 10⁹ CFU/kg of C. butyricum + 10⁹ CFU/kg of B. coagulans (E1) and 10⁹ CFU/kg of C. butyricum + 10⁹ CFU/kg of B. coagulans + 100 g/kg of APS (E2) as experimental diets. The results indicated that both E₁ and E₂ diets increased specific growth rate, reduced feed conversion ratio, and optimized muscle composition. Compared with the control treatment, after trout were fed with E₂ diet 42 days, activities of SOD, T-AOC, and CAT increased significantly, while malondialdehyde content decreased significantly in the E1 treatment. After Aeromonas salmonicida challenge, cumulative mortality was 80%, 41%, and 29% in C0, E1 and E₂ treatments, respectively. The abundance of Bacillales, Actinomycetales, and Pseudomonadales increased in the fish intestine of E₂ treatment, while that of Rhodobacterales and Rhizobiales decreased. These data showed that C. butyricum + B. coagulans with APS improved growth performance, enhanced immunity and disease resistance, and modulated intestinal microbiota of O. mykiss.

中文翻译：

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含中草药多糖的膳食益生菌对虹鳟鱼（Oncorhynchus mykiss）生长性能、免疫力、抗病性和肠道菌群的潜在影响

本研究评估了益生菌（丁酸梭菌、凝结芽孢杆菌）和中草药多糖（黄芪多糖，APS）对虹鳟鱼（Oncorhynchus mykiss）生长性能、免疫力、抗病性和肠道微生物群的影响。O. mykiss ( n  = 360; 79.9 ± 2.2 g) 的样本用包含基础饮食（对照，C0）的不同饮食喂养 42 天，补充有 10 ⁹  CFU/kg 的丁酸梭菌 + 10 ⁹  CFU/kg的凝结芽孢杆菌（E1）和10 ⁹  CFU /公斤的丁酸梭菌 + 10 ⁹  CFU /公斤的B. 凝结物 + 100 g/kg APS (E2) 作为实验饮食。结果表明，E ₁和E ₂日粮均提高了比生长率，降低了饲料转化率，并优化了肌肉成分。与对照处理相比，E ₂日粮饲喂鳟鱼42 d后，E1处理中SOD、T-AOC和CAT活性显着升高，丙二醛含量显着降低。在杀鲑气单胞菌攻击后，C0、E1 和 E ₂处理的累积死亡率分别为 80%、41% 和 29% 。E ₂鱼肠中芽孢杆菌、放线菌和假单胞菌的丰度增加处理，而红杆菌和根瘤菌的减少。这些数据表明，C. butyricum  +  B. coagulans与 APS 提高了生长性能，增强了免疫力和抗病性，并调节了O. mykiss 的肠道微生物群。