Effects of a diet high in resistant starch on fermentation end-products of protein and mucin secretion in the colons of pigs

The fermentation of protein in the hindgut of humans and animals is associated closely with the host health. This study was conducted to investigate the effects of long-term intake of a diet high in resistant starch (RS) on the fermentation end-products of protein and mucin secretion in the colons of pigs. Thirty-six Duroc x Landrace x Large White growing barrows were randomly allocated to corn starch (CS) and raw potato starch (RPS, high in RS) groups. Pigs in the CS group were offered a corn-soybean-based diet, while pigs in the RPS group were put on a diet in which 230 g/kg (growing) or 280 g/kg (finishing) purified CS was replaced with purified RPS during a 100-day trial. At the age of 170 days, the digesta and mucosa samples from the colons of pigs were collected for the chemical and gene expression analysis. Results showed that long-term intake of RPS diet increased crude protein and mucin contents in the colons of pigs (p< 0.05), and decreased total amino acids, ammonia-nitrogen, tryptamine, tyramine, branched-chain fatty acid, phenol, cresol, indole, and skatole concentrations (p< 0.05) when compared with the CS diet. Real-time PCR assay showed that RPS diet up-regulated the expression of mucin genes MUC4, MUC5AC, and MUC12 in the colons of pigs (p< 0.05). These results suggest that long-term intake of RS diet may improve the hindgut health by increasing the mucin secretion and reducing the harmful fermentation of protein although causing more nitrogen losses in pigs.