Diet composition, especially non-digestible nutrients such as dietary fibre, resistant starch, and non-digestible and endogenous proteins, is one of the major determinants of intestinal microbial composition, because the metabolic repertoire and nutrient requirements of members of the bacteria are widely different. Dietary inclusion of fermentable carbohydrates (fCHO) yields short chain fatty acids which are considered beneficial to the host and also reduce large intestinal formation of putatively toxic metabolites derived from fermentable proteins (fCP). In contrast, amino acids are fermented to a variety of products, the majority of them, associated with toxic and pro-inflammatory impacts on the intestinal epithelium. However, the effect of feeding diets high in fCP concentration on epithelial response and interaction with fCHO is still unclear. The aim of the present study was to determine the effect of fermentable protein from heat-damaged soybean meal and fermentable fibre from wheat bran and sugar beep pulp and their interaction on large intestinal microbial fermentation patterns, colonic oxidative stress, and cytokine response markers in weaned piglets. Thirty-two weaned piglets were fed 4 diets in a 2 x 2 factorial design with low fCP/low fCHO [14.5% crude protein (CP)/14.5% total dietary fibre (TDF)]; low fCP/high fCHO (14.8% CP/16.6% TDF); high fCP low fCHO (19.8% CP/14.5% TDF); and high fCP/high fCHO (20.1% CP/18.0% TDF) as dietary treatments. After 21–23 d, pigs were euthanized and colon digesta and tissue samples were analyzed for indices of microbial ecology, tissue expression of genes for cell turnover, cytokines, mucus genes (MUC), and oxidative stress indices.
Pig performance was unaffected by the dietary treatment. fCP increased (P < 0.05) cell counts of clostridia in the Clostridium leptum group and total short and branched chain fatty acids, ammonia, putrescine, histamine, and spermidine concentrations, whereas high fCHO increased (P < 0.05) cell counts of clostridia in the C. leptum and C. coccoides groups, shifted the acetate to propionate ratio toward acetate (P < 0.05), and reduced ammonia and putrescine (P < 0.05). High dietary fCP increased (P < 0.05) expression of PCNA, IL1b, IL10, TGFb, MUC1, MUC2, and MUC20, irrespective of fCHO concentration. The ratio of glutathione:glutathione disulfide was reduced (P < 0.05) by fCP and the expression of glutathione transferase was reduced by fCHO (P < 0.05).
In conclusion, fermentable fibre reduce fermentable protein-induced changes in most measures of luminal microbial ecology but not the mucosal response in the large intestine of pigs.
R Pieper, S Kröger, JF Richter, J Wang, L Martin, J Bindelle, JK Htoo, D von Smolinski, W Vahjen, J Zentek, AG Van Kessel. Fermentable fibre ameliorates fermentable protein-induced changes in microbial ecology, but not the mucosal response, in the colon of piglets. 2012. Journal of Nutrition, 142(4):661-667.