| This dissertation presents the impact of dietary fibers on neonatal intestinal development and function in health and disease using the piglet model. The first study investigated whether dietary fibers would influence normal intestinal development in piglets receiving either formula alone (CON) or containing methylcellulose (MCEL; nonfermentable), soy-polysaccharides (SPS; moderately-fermentable), or fructo-oligosaccharides (FOS; highly-fermentable) for 0, 7 or 14d. Total short-chain-fatty-acids concentrations, indicating the fermentability of fibers in the formulas, were higher in the colon of piglets fed SPS and FOS. However, the addition of dietary fibers to infant formula did not alter normal intestinal structural and functional development.; The next study investigated the effect of dietary fiber in a model of intestinal disease. Piglets were randomized to receive the same diets as described above for 14d. On d7, piglets were further randomized to receive an oral dose of Salmonella typhimurium (1010 CFU) or to serve as non-infected controls. Piglets fed SPS and FOS had less diarrhea, improved physical activity and ileal lactase activity, whereas postinfection mucosal barrier function was maintained or improved in MCEL-groups, indicating that different types of dietary fibers can benefit the intestine.; Finally, the potential mechanisms underlying the preventative effects of fibers by characterizing the innate and adaptive immune responses to S. typhimurium infection was investigated. Piglets were randomized into the previous four diet groups, were infected on d7, and samples were taken at 0, 4, 12, 24, and 48h post-infection. Piglets fed FOS displayed a greater number of sulfo-acidomucin-secreting goblet cells and reduced serotonin-induced chloride secretion compared to the other groups before infection, suggesting resistance to infection. Pre-infection ileal mRNA expression of IL-1beta and IL-6 was greater in all fiber groups compared to CON. IL-8 expression was greater in piglets fed-FOS compared to other groups, whereas NFkB was inhibited, suggesting that FOS enhances the innate mucosal immunity prior-infection and attenuates post-infection adaptive immunity.; In summary, dietary fibers with different degrees of fermentability prevented S. typhimurium-infection-associated symptoms in piglets, maintained intestinal structure and function, enhanced innate and adapted immune response, and its addition to formula, could provide a cost-effective means to prevent and/or reduce bacterially-induced diarrheal diseases in neonates. |
