UCP1 and immune system disorder: The results showed that the microbiota in UCP1-HFHC group pigs have a low abundance of functional annotation of immune system diseases (primary immunodeficiency) and high abundance of functional annotation of the immune system (antigen processing and presentation) and cell motility (bacterial motility proteins) compared with the WT-HFHC group pigs after 3 months (P < 0.05) (Fig. 2J and Table S2) and 8 months (P < 0.05) (Fig. 2K and Table S2) of the HFHC diet treatment, respectively.