Galacto-oligosaccharides modulate the juvenile gut microbiome and innate immunity to improve broiler chicken performance

ABSTRACT Improvements in growth performance and health are key goals in broiler chicken production. Inclusion of prebiotic galacto-oligosaccharides in broiler feed enhanced the growth rate and feed conversion of chickens relative to a calorie-matched control diet. Comparison of the cecal microbiota identified key differences in abundance of Lactobacillus spp. Increased levels of L. johnsonii in GOS-fed juvenile birds at the expense of L. crispatus was linked to improved performance (growth rate and market weight). Investigation of the innate immune responses highlighted increases of ileal and cecal IL-17A gene expression counterposed to a decrease in IL-10 and IL-17F. Quantification of the autochthonous Lactobacillus ssp. revealed a correlation between bird performance and L. johnsonii abundance. Shifts in the cecal populations of key Lactobacillus spp. of juvenile birds primed intestinal innate immunity without harmful pathogen challenge. IMPORTANCE Improvements in the growth rate of broiler chickens can be achieved through dietary manipulation of the naturally occurring bacterial populations whilst mitigating the withdrawal of antibiotic growth promoters. Prebiotic galacto-oligosaccharides (GOS) are manufactured as a by-product of dairy cheese production, which can be incorporated in the diets of juvenile chickens to improve their health and performance. This study investigates the key mechanisms behind this progression and pin points L. johnsonii as a key species that facilitates the enhancements in growth rate and gut health. It also relates the role of the innate immune system in the response to the GOS diet.