Abstract:This study performed rational feeding of fermented feed to channel catfish and determined its effects on growth, the intestinal bacterial community, and metabolomics of channel catfish. There were three groups: continuous feeding (A, continuous addition of fermented feed to the puffed feed), interval feeding involving weekly intervals addition of fermented feed added to the puffed feed (B), and the control group only fed the puffed feed (C). The experiment lasted 6 months. Channel catfish were weighed and the intestinal flora and metabolomics were detected by 16S rRNA sequencing technology and liquid chromatography-based metabolomics technology, respectively after the experiment. The final body weight (FBW) of channel catfish was significantly higher in the interval feeding group than that in the control group and the continuous feeding group (P<0.05). The richness and microbial diversity of the intestine was the highest in the interval feeding group, while the richness of the continuous feeding group was the lowest (P>0.05). Firmicutes, Actinobacteriota, Cyanobacteria, Proteobacteria, Fusobacteriota, Chloroflexi, and Deinococcota were the dominant bacterial phyla among the intestinal flora. The dominant intestinal genera included norank_f_norank_o_Chloroplast, Mycobacterium, Cetobacterium, Romboutsia, Exiguobacterium and Clostridium_sensu_stricto_1. Metabolomic analysis showed that the continuous feeding group mainly affected galactose metabolism and the phosphotransferase system of the intestinal flora in channel catfish through the significant upregulation of N-acetyl-D-galactosamine (P<0.05) that affected the digestion and absorption of carbohydrates by fish. The differential metabolites L-serine and L-phenylalanine were significantly upregulated (P<0.05) in the interval feeding group. This affected sulfur metabolism and amino acid metabolism of the intestinal flora, and affected energy absorption, anti-inflammation, and immunity of the channel catfish. This study provided a theoretical basis for the exploration of feeding methods using fermentation feed and healthy green breeding of channel catfish.
