Integrated metagenomics-metabolomics analysis reveals the cecal microbial composition, function, and metabolites of pigs fed diets with different starch sources

This study integrated metagenomics and metabolomics to evaluate the effects of diets with different starch sources on the microbial community, metabolic functions, and resultant metabolites in the cecum of finishing pigs. In this study, 48 crossbred growing barrows were randomly allocated to 2 treatment groups with eight replicate pens of 3 pigs each. Pigs were fed a tapioca starch (TS) diet or a pea starch (PS) diet (the ratio between amylose and amylopectin of the two diets were 0.11 and 0.44, respectively) for 44 days. The results showed that, compared with the TS diet, the PS diet increased (P < 0.05) the relative abundance of amylolytic bacteria, such as Lactobacillus spp., and Streptococcus spp., and decreased (P < 0.05) the relative abundance of some inflammatory bacteria, such as Tyzzerella, Porphyromonas, and Tannerella in the cecum of pigs. In addition, analysis of microbial functions showed that 11 carbohydrate-active enzymes, such as GH73, AA3, and AA6, were enriched in the PS group (P < 0.05), while 26 other enzymes, such as GH2, GH35, and GH53, were enriched in the TS group (P < 0.05). Meanwhile, KEGG pathway analysis showed a decreasing trend (P < 0.1) for energy metabolism and amino acid metabolism pathways, and a significant increase (P < 0.05) in the lipid metabolism pathways in the PS group. Correspondingly, the resultant metabolites related to amino acids and their derivatives (such as decreased histamine and indole, while increased γ-aminobutyric acid and pyroglutamic acid), and fatty acids and lipids (such as increased tetradecanoylcarnitine and monoacylglycerol) were also changed (P < 0.05) in the cecum of pigs fed the PS diet. In summary, these findings indicated that the cecal microbiota and metabolism underwent responsive changes to diets with different starch sources, and a high ratio of amylose to amylopectin in diets may be beneficial to intestinal health of pigs.