The physiological role of the gastrointestinal microbiota has become an important subject of nutrition research in pigs in the past years, and the importance of intestinal microbial activity in the etiology of disease is doubtless. This review summarizes the recent knowledge related to the microbial ecology of protein fermentation and the appearance of protein-derived metabolites along the pig intestine. The amount of fermentable protein depends on factors such as dietary protein concentration, protein digestibility due to secondary or tertiary structure, the interaction with dietary compounds or anti-nutritional factors, and the secretion of endogenous proteins into the gut lumen. High protein diets increase the luminal concentrations and epithelial exposure to putatively toxic metabolites and increase the risk for post-weaning diarrhea, but the mechanisms are not yet clarified. Although the use of fermentable carbohydrates to reduce harmful protein-derived metabolites in pigs is well-established, recent studies suggest that the inclusion of fermentable carbohydrates into diets with low protein digestibility or high dietary protein level may not ameliorate all negative effects with regard to epithelial response. Based on the current knowledge, the use of diets with low levels of high-quality protein may help to reduce the risk for intestinal disease in young pigs.

The aim of the present work was to study the influence of tannic acid (TA) and protein level in the diet on fermentation in the caecum of rats, activity of bacterial β-glucuronidase, and colon morphology. Twelve groups of six male Wistar rats were given either a control diet free of TA or diets...

The study aimed at determining the effect of two types of prebiotics and a multispecies probiotic on microbiota activity and composition, as well as mucosal immunity in the large intestine of young pigs. In total 48 piglets were divided into 6 groups (n = 8), which received from day 10 of life probiotic-unsupplemented (PU) or probiotic-supplemented (PS) diets. Probiotics were added at 0.5 g/kg diet and contained: Lactococcus lactis, Carnobacterium divergens, Lactobacillus casei, Lactobacillus plantarum and Saccharomyces cerevisiae. The PU and PS diets were formulated without prebiotic addition (control) or with addition of 2% of inulin from chicory root (IN) or 4% of dried Jerusalem artichoke tubers (DJA). After 40 days of feeding, digesta and tissue samples were taken from the caecum and three sections of the colon for analyses of microbiota activity and composition, secretory immunoglobulin A (sIgA) and intraepithelial lymphocytes (IEL). IN diets decreased the caecal digesta pH and β-glucosidase activity but increased propionic, valeric and total short chain fatty acid (SCFA) concentrations compared to control diets. Feeding DJA diets increased caecal valeric acid level, decreased the concentration of isoacids in the colon, reduced β-glucosidase and β-glucuronidase activity in the middle colon and increased Bifidobacterium spp. populations in the proximal and distal colon. PS diets increased the caecal acetic acid and total SCFA level, and Clostridium spp. populations in the distal colon. Neither probiotic nor prebiotics affected sIgA level or IEL number in the large intestine. In conclusion, DJA modified the microbiota ecology in the large intestine of young pigs to a greater extent than IN and the applied probiotic did not enhance effects of prebiotics.

The use of pea seeds is limited due to the content of antinutritional factors that may affect gut physiology. Heat treatment such as extrusion may reduce heat-labile antinutritional factors and improve the nutritional value of pea seeds. This study determined the effect of partial replacement of soybean meal in pig diets by raw or extruded pea seeds on growth performance, nitrogen balance and physiology of the ileum and distal colon. The experiment was carried out in 18 castrated male piglets of initial body weight of 11 kg, divided into three groups. The animals were fed cereal-based diets with soybean meal (C), which was partly replaced by raw (PR) or extruded pea (PE) seeds. Nitrogen balance was measured at about 15 kg body weight. After 26 days of feeding, tissue samples were taken from the ileum and distal colon for histological measurements, and colonic digesta samples for analyses of microbial activity indices. The animals fed the PE diet had a significantly greater average daily gain than those fed the C diet and better apparent protein digestibility than those on the PR diet. Pigs fed the PR diet had a significantly greater butyric acid concentration and lower pH in the colon than pigs fed PE and C diets. There was no significant effect of the diet on other indices of microbial activity or morphological parameters. In conclusion, feeding a diet with extruded pea seeds improved growth performance of pigs, did not affect intestinal morphology and had a negligible effect on microbial activity in the distal colon.