A lactobacilli-based probiotic but not its postbiotic reduces intestinal inflammatory pathways expression in broilers fed a non-starch polysaccharide rich challenge diet

Diets rich in non-starch polysaccharides (NSP) are known to challenge broiler growth and induce gut inflammation. Here, a lactobacilli-based probiotic (Pro) and its derived postbiotic (Post) were investigated when supplemented to an NSP-rich challenge diet (Ctrl) fed to broilers reared under commercial conditions. Treatments had 8 pen replicates with 40 broilers each. On day 35, for 3 broilers/pen, the microbiota, volatile fatty acids and semi-polar metabolome composition were determined in ileal and caecal digesta. In addition, changes in the transcriptome of jejunal, ileal and caecal tonsil tissues as well as in the blood were investigated by RNA-seq. Apparent ileal nutrient digestibility and tibia health were also assessed. The Pro affected the relative abundance of four operational taxonomic units (OTU) in ileal and none in caecal digesta. The Post affected the relative abundance of nine OTU in ileal and two in caecal digesta. Microbiota diversity indexes and the semi-polar metabolome were not affected by Pro and Post. According to gene set enrichment analysis of Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, the jejunal tissue transcriptome of Pro v.s. Ctrl birds had upregulated pathways linked to cell activity, energy production and DNA transcription. In ileal tissue, similar pathways had a significant enrichment score. In jejunal tissue, downregulated pathways with Pro were linked to immunity and inflammation. In caecal tonsil tissue, Pro was associated with a negative enrichment score of immune and detoxification-related pathways in KEGG and GO. The Pro had minor effects on the blood transcriptome. Compared to Ctrl, Post had minor effects on the jejunal, ileal and caecal tonsil tissues transcriptome, and no effects on the blood transcriptome. Overall, Pro and Post elicited different physiological effects with Pro but not Post supplementation inducing a clear pattern of potential mechanisms. Results indicate that the lactobacilli-based probiotic induced beneficial effects by lowering inflammation in the gut, and that these effects likely originate from the more proximal intestine.