Prebiotic galactooligosaccharide feed modifies the chicken gut microbiota to efficiently clear .

Unlabelled: Chicken meat is contaminated with from the gut of infected chickens during slaughter. Eradication of from broiler chickens through hygiene measures and/or vaccination is not cost-effective; complementary approaches are required. A mature gut microbiota obstructs infection in chickens, and deliberate fortification of colonization resistance through prebiotic feed formulations would benefit public health and poultry production. Prebiotic galactooligosaccharides hastens clearance from the gut of infected chickens. To better understand the role of galactooligosaccharides in colonization resistance, broiler chickens were raised on a wheat-soybean meal-based feed, with or without galactooligosaccharides for the first 24 days of life. Chickens were orally challenged with serovar Enteritidis at 20 days and the effect of supplementary galactooligosaccharides characterized by profiling colonization, gut microbiota, innate immune response, and cecal short-chain fatty acid concentrations. Exposure to dietary galactooligosaccharides shortened the time to clear . Enteritidis from the ceca. Differential abundance analysis of the cecal microbiota associated challenge with a bacterial taxon belonging to the Acidaminococcaceae family ( < 0.005). Increased cecal concentrations of the short-chain fatty acids propionate and valerate were measured in -challenged chickens sustained on either control or galactooligosaccharide-supplemented feed relative to mock-challenged controls; but far greater concentrations were detected in chickens fed a galactooligosaccharide-supplemented diet in early life. The abundance of the Acidaminococcaceae taxon exhibited a positive correlation with the cecal concentrations of propionate (ρ = 0.724, = 0.008) and valerate (ρ = 0.71, = 0.013). The absence of cecal pro-inflammatory transcriptional responses suggest that the rapid clearance observed for the galactooligosaccharide-supplemented diet was not linked to innate immune function.

Importance: Work presented here identifies bacterial taxa responsible for colonization resistance to in broiler chickens. Deliberate cultivation of these taxa with prebiotic galactooligosaccharide has potential as a straight-forward, safe, and cost-effective intervention against . We hypothesize that catabolism of galactooligosaccharide and its breakdown products by indigenous microorganisms colonizing the chicken gut produce excess levels of propionate. In the absence of gross inflammation, propionate is inimical to and hastens intestinal clearance.