Potential effects of dietary probiotics with Chinese herb polysaccharides on the growth performance, immunity, disease resistance, and intestinal microbiota of rainbow trout (Oncorhynchus mykiss)

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 10(9) CFU/kg of C. butyricum + 10(9) CFU/kg of B. coagulans (E1) and 10(9) CFU/kg of C. butyricum + 10(9) CFU/kg of B. coagulans + 100 g/kg of APS (E2) as experimental diets. The results indicated that both E-1 and E-2 diets increased specific growth rate, reduced feed conversion ratio, and optimized muscle composition. Compared with the control treatment, after trout were fed with E-2 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 E-2 treatments, respectively. The abundance of Bacillales, Actinomycetales, and Pseudomonadales increased in the fish intestine of E-2 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.

Automated summary

The study evaluated the impact of probiotics and Chinese herb polysaccharides on growth performance, immunity, disease resistance, and intestinal microbiota of rainbow trout. Results showed that the experimental diets improved growth performance, enhanced immunity, and disease resistance, while modulating the intestinal microbiota of O. mykiss.