Fecal Microbial Changes in Response to Finishing Pigs Directly Fed With Fermented Feed

The present study investigated the effects of fermented complete feed (FCF) on fecal microbial composition during the grower-finisher period. A total of 20 pigs (Duroc × Landrace × Yorkshire, 48.74± 1.49 kg) were divided randomly into two groups: the CN group (pigs fed with a basal diet) and the FCF group (pigs fed with FCF). After a 60-day trial period, 3 pigs with middle-weight from each treatment were selected for fecal sampling and fecal microbiota analysis. The results showed that the FCF significantly increased operational taxonomic units (OUT) numbers, alpha diversity (Simpson index and Shannon index), and beta diversity, which means that FCF increased the fecal microbiota diversity. At the phylum level, the abundance of Tenericutes, Spirochaetae, Verrucomicrobia, and Cyanobacteria were changed in pigs fed with FCF; and at the genus level, the abundance of Christensenellaceae_R-7_group, Treponema_2, Ruminococcaceae_UCG-005, Prevotellaceae_UCG-003, Phascolarctobacterium, Roseburia, and Prevotella_9 were changed in pigs fed with FCF. The linear discriminant analysis effect size (LEfSe) analysis showed that Roseburia and Prevotella_9 genera were increased, while Tenericutes phyla and Streptococcus, Christensenellaceae_R-7_group, and Lactobacillus genera were decreased in the FCF group compared to the CN group. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) results predicted that the relative abundance of infectious diseases: parasitic associated genes, xenobiotics biodegradation, and metabolism-associated genes were significantly reduced in the FCF group when compared with the CN group, and the relative abundance of signal transduction associated genes, amino acid metabolism-related genes, and replication and repair associated genes were significantly higher in the FCF group when compared with the CN group. In addition, the relative abundance of transport and catabolism-associated genes, membrane transport-associated genes, and biosynthesis of other secondary metabolite-associated genes tended to be higher in the FCF group when compared with the CN group; and the relative abundance of immune diseases associated genes tended to be lower in the FCF group when compared with the CN group. In conclusion, the FCF influenced the alpha and beta diversity of the fecal microbiota of pigs.