Comparison of the content of SCFAs and AAs among different samples of the five groups. (A) Total SCFA concentration, (B) content of acetic, propionic and butyric acid, (C) acetic acid/propionic acid ratio, (D) acetic acid/butyric acid ratio and (E) propionic acid/butyric acid ratio in different samples. (F-H) Total content of AAs in (F) feces, (G) ileocecal content and (H) blood samples, respectively; (I-K) Content of branched chain amino acids in (I) feces, (J) ileocecal content and (K) blood samples, respectively. *P<0.05 vs. two assigned groups, #P<0.05 vs. one assigned group compared with the other groups. Groups: CON, normal control diet; PRO, high-protein diet; FIB, high-fibre diet; SUG, high-sugar diet; FAT, high-fat diet. SCFA, short-chain fatty acids; AA, amino acids.