Fermented mixed feed regulates intestinal microbial community and metabolism and alters pork flavor and umami

This study aimed to determine the effects of fermented mixed feed (FMF) supplementation (0%, 5% and 10%) on the intestinal microbial community and metabolism, and the compositions of volatile flavor compounds and inosine monophosphate (IMP) contents in the longissimus thoracis. In this study, 144 finishing pigs (Duroc x Berkshire x Jiaxing Black) were randomly allocated to 3 groups with 4 replicate pens per group and 12 pigs per pen. The experiment lasted 38 days after 4 days of acclimation. The 16S rRNA gene sequences and an untargeted metabolomics analysis showed FMF altered the profiles of microbes and metabolites in the colon. Heracles flash GC e-nose analysis showed that 10% FMF (treatment 3) had a greater influence on the compositions of volatile flavor compounds than 5% FMF (treatment 2). Compared to 0% FMF (treatment 1), the contents of total alde-hydes, (E,E)-2,4-nonadienal, dodecanal, nonanal and 2-decenal were significantly increased by treatment 3, and treatment 3 increased IMP concentrations and gene expressions related to its synthesis. Correlations analysis showed significantly different microbes and metabolites had strong correlations with the contents of IMP and volatile flavor compounds. In conclusion, treatment 3 regulated intestinal microbial community and metabolism, that in turn altered the compositions of volatile compounds, which contributed to improving pork flavor and umami.