Health and functions of the gastrointestinal tract in pigs: Effects of functional ingredients and feed and ingredient processing

This paper provides a review on the effects of functional ingredients and processing of ingredients and diets on the functions of the gastrointestinal tract (GIT) and health of the GIT in pigs. There is increasing attention for these topics since the ban of in-feed growth promoting antibiotics in many parts of the world and due to the pressure on the use of antibiotics in animal production. A prime function of the GIT is to digest and absorb nutrients. In addition, it has a complex barrier function of which the intestinal microbiota and the residing local immune system are important components. The health of the GIT is related to the capacity of the GIT to exert these functions. Ingredient and nutrient composition of the diet affect the various functions of the GIT and, therefore, also influence GIT health. Feed and feed ingredient processing can affect the extent and site of enzymatic nutrient digestion within the small intestine but can also induce changes in the extent of fermentation of dietary constituents by intestinal microbiota and induce changes in microbiota composition in various segments of the GIT. Further understanding of the mechanisms involved in the complex interactions among the diet, intestinal microbiota, and intestinal tissue can assist in supporting functions of the GIT and health of the GIT via targeted modifications of the diet.