Long-Term Consumption of Soluble Dietary Fibre Increases Activation of the Immune System in Broilers Chickens

Long-term feeding of dietary fibre (DF) has been reported to cause erosion of the epithelial cell layer resulting in mucosal damage with a decrease in villus height in the small intestine (Iji et al., 2001). This project studied the long-term effects of low and high levels of soluble DF on gut physiology by comparing transcriptome in the jejunum between groups. We hypothesized that soluble DF would cause an increase in immune system activity and result in an increased inflammatory response in the gastrointestinal tract (GIT).

A corn/soy-based mash diet was used with or without DF supplementation consisting of 0.5% xylo-oligosaccharide (XOS) and 1% arabinoxylan-rich fraction (AXRF) of wheat. Each treatment was randomly distributed across eight pens (n=8) with eight chickens each. At the end of the 42-day experiment, there were no significant differences for growth between the two treatment groups. At day 42, one chicken per pen was selected based on average weight and jejunum samples were collected for transcriptomics analysis. Standard RNA-seq protocols were used to identify differentially expressed genes (DEGs) and the Database for Annotation, Visualization and Integrated Discovery to identify enriched pathways. Results showed more than 450 DEGs (P < 0.05). The DEGs of interest associated with the immune response are shown in Table 1. CD40LG, a factor inducing differentiation of IgM+ naïve B cells into IgA+ B cells was upregulated (P < 0.05) in chickens fed with high levels of DF. IL8L1, a mediator of the inflammatory response, was also upregulated (P < 0.05). DEGs showed enriched pathways associated with the intestinal immune network for IgA production and the inflammatory response (Table 1).

In conclusion, long-term dietary supplementation with XOS and AXRF increased immune system activity, involving specific (IgA production) and non-specific (inflammatory response) defence mechanisms in the GIT of broiler chickens.

ACKNOWLEDGEMENTS: This study has been funded by AB Vista.