There is a growing body of evidence that is linking the interactions between diet, intestinal microbiota, and the pig’s immune system. These interactions have broad implications on pig health. Prebiotics are dietary compounds that can promote the growth of pig health friendly microbes in preference to disease causing microbes. Dietary prebiotics, such as resistant (potato) starches are minimally digested by the host and commensal microbes in the small intestine. Because of this they can make their way downstream to the large intestine where they are available to the microbes as accessible carbohydrates.
When these fermentable carbohydrates become depleted the large intestine bacteria often shift from utilizing diet-derived carbohydrates to harvesting host-derived sugars from the pig’s intestinal mucus layer. If the rate of utilization outpaces the rate of replenishment, the pig’s immune system “barrier function” can be compromised. When dietary carbohydrates are available microbes will also ferment the carbohydrates into beneficial metabolites such as short-chain fatty acids (SCFAs). These SCFAs such as butyrate are consumed by the pigs intestinal cells as a source of fuel which then allows for increased secretion of protective mucus, pathogen killing antimicrobial peptides and immunoglobulin A. In this study, the researchers fed the pigs either a diet amended with 5% resistant potato starch (RPS) or an unamended control diet (CON).
The researchers discovered that RPS in the diet intake increased the abundance of anaerobic Clostridia in feces and several tissues intestinal butyrate concentrations regulatory T cells in the large intestine and imune status alterations were indicative of enhanced mucosal defenses. regulatory T cells that positively correlated with butyrate concentration, luminal IgA concentration, expression of IL-6 and DEF1B, and several mucosa-associated bacterial taxa.
Take Home Message
- RPS inclusion in feed modulated the microbiota and host immune status through alterations in large intestine barrier function and immunological tolerance
- RPS reduced the favourable environment for bacteria such as Salmonella, and Escherichia species that utilize bacterial respiration rather than fermentation.
- Because there was no specific disease challenge in this model there were no differences in pathological lesions in this study but testing this finding in a disease challenge model would be a logical next step.
Submitted by Brent Jones, DVM
Ref: Trachsel J, Briggs C, Gabler NK, Allen HK, Loving CL.Dietary Resistant Potato Starch Alters Intestinal Microbial Communities and Their Metabolites, and Markers of Immune Regulation and Barrier Function in Swine.Front Immunol. 2019 Jun 19;10:1381. doi: 10.3389/fimmu.2019.01381. eCollection 2019.