Effects of dietary fibres on gut microbial metabolites and liver lipid metabolism in growing pigs.

This study was conducted to investigate the effects of dietary supplementation with wheat bran fibre, inulin and their combination on growth performance, short-chain fatty acids (SCFAs) production in caecum and colon and liver lipid metabolism in growing pigs. A total of 48 Duroc × Landrace × Yorkshire cross-bred growing pigs (73 ± 2 days of age; 24.37 ± 2.86 kg) were allocated to four groups randomly, each group consisting of six pens with two pigs each. The pigs were fed a control diet (CON), a diet containing 2% wheat bran fibre (WB), a diet containing 2% inulin (IN), and a diet containing both of 1% wheat bran fibre and 1% inulin (MIX), respectively. The trial lasted for 28 days. The results showed that MIX fed pigs had a higher percentage of fat in the liver than those fed the CON (p < .05). IN, WB or MIX feeding decreased the concentrations of acetate and total SCFAs in colon compared with CON (p < .01). Feeding WB or IN also decreased the colonic butyrate concentrations compared with CON (p < .01). However, the serum level of valeric acid was elevated in the IN, WB and MIX group (p < .01). MIX fed pigs tended to have lower levels of propionate in serum than the WB fed pigs (p = .098). MIX feeding enhanced the mRNA expression of lipid synthesis-related genes in liver compared with CON (p < .05). Feeding IN decreased the expression of bile acids synthesis-related genes in liver and increased mRNA expression of SCFAs transporter SLC16A1 in colon compared with CON (p < .05). In this study, these data indicated that the combined supplementation of wheat bran fibre and inulin decreased the SCFAs concentrations in the colon, enhanced the genes FAS and HNF-4α mRNA expression in liver and induced liver lipid accumulation in growing pigs.