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Use of dietary carbohydrates as prebiotic in swine diets
Using dietary antibiotics as growth promotant will be reduced; thus, dietary alternatives are being investigated. Dietary carbohydrates include oligosaccharides, starch, and fiber (non-starch polysaccharides) and these may be part of a toolkit to manage gut health in pigs. Antibiotics are hypothesized to control gut health via manipulations of intestinal microbial profiles but may also reduce intestinal inflammation. Oligosaccharides may be rapidly fermented and thereby influence intestinal microbial profiles and metabolite production. Specific exopolysaccharides from Lactobacillus reuteri may serve as scavenger molecules for pathogenic bacteria, e.g., enterotoxigenic E. coli (ETEC), to bind to instead of adhering to the gut wall, thereby avoiding diarrhea initiation by ETEC. Starch is mostly digested and absorbed as glucose; however, resistant starch is not digested but fermented. Resistant starch acts as fiber but is unique, because it 1) specifically increases digesta content of bifidobacteria that have been associated with improved gut health and 2) is completely fermented within the gut. Sources of fiber differ in their 2 key characteristics: viscosity and fermentability. Increased viscosity has been associated with increased gut content of virulence factors that are linked with diarrhea. Increased kinetics of fiber fermentation is associated with changes in microbial profiles and increased metabolite production. Recently, microbial composition was hypothesized to be less important and the focus should be on their combined output of metabolites. Raw materials and prebiotic feed additives both influence kinetics of fermentation and have prebiotic activity. Their kinetics of fermentation should be quantified so that it can be included in feed formulation. In conclusion, dietary carbohydrates via their prebiotics activity are part of the solution to remove antibiotics as growth promotant from swine diets.
Keywords: carbohydrate, gut health, pig