Effects of dietary soybean meal on the intestinal microbiota and metabolic enzymes activities of microbial amino acids of Channa argus

This study aimed to investigate the effect of soybean meal on the growth, intestinal microbiota composition and metabolic enzymatic activities of microbial amino acid of Channa argus. Four isonitrogenous and isoenergetic diets were formulated with soybean meal by replacing 0, 25%, 50% and 75% fish meal (G1, G2, G3 and G4, respectively). The fish of (8.65±0.25) g was hand-fed daily to satiation twice in cylindrical fiberglass tanks for 21 days. Results showed that no significant difference in survival rate was found among four groups. The growth performance of C. argus in G4 was significantly lower than those in G1 and G2, while the difference was not statistically significant between G3 and other three groups. The proportion of Firmicutes in the intestine of fish in G1 and G2 was significantly higher than that in G3, and the lowest was found in G4. The proportion of Proteobacteria in G1 and G2 was significantly lower than those in G3 and G4. The proportion of Lactococcus, Bacillus, Pseudomonas, Streptococcus, Laseczka and Acinetobacter in G4 was significantly lower than those in the other three groups. Additionally, the activities of glutamic-pyruvic transaminase and adenosine deaminase were the the highest in G4, while the activity of lactic dehydrogenase was the the highest in G1. All results indicated that, except for the effect on the growth of C. argus, dietary soybean meal significantly induced the changes in the intestinal microbiota composition and the activity of the microbial amino acid metabolic enzymes, which may provide theoretical basis for further understanding the application of soybean meal in the formulated diets of C. argus.