Exposure to plant-oriented microbiome altered jejunal and colonic innate immune response and barrier function more strongly in suckling than in weaned piglets.

Creep feed is offered during the suckling period to prepare the piglet's gut for the dietary transition from a milk- to a plant-based diet at weaning. Nevertheless, the discontinuation of sow milk consumption after weaning can lead to disturbed interactions between the host mucosa and the gut microbiota. Little information is available on the immediate mucosal response towards the altered microbial and metabolite composition in digesta. Therefore, the main objective of this study was to evaluate the immediate effect of the exposure of the jejunal and colonic mucosa to a plant-oriented microbiome (POM), prepared from intestinal digesta of weaned pigs, on the mucosal structure, secretory response, and permeability in piglets before and after weaning using the intestinal loop perfusion assay. The perfusion with POM stimulated the host's secretory response, altered the gut structure and decreased the epithelial integrity before and after weaning. Effects were less strong postweaning, indicating that adaptation processes at the gut epithelium occurred from pre- to postweaning which increased the tolerance towards the POM inoculum.