Integrated transcriptomic and metabolomic analysis of immune and metabolic pathways in broiler chickens supplemented with Lactobacillus reuteri and Streptomyces coelicolor.

The overuse of antibiotics in poultry production has raised global concerns on antimicrobial resistance thereby increasing the need for effective and sustainable alternatives such as probiotics. Although previous research reveals that Lactobacillus reuteri and Streptomyces coelicolor supplementation improves performance metrics in broiler chickens, the molecular mechanisms contributing to these outcomes remain unclear. The goal of this study was to assess the transcriptomic and metabolomic responses of broiler chickens fed diets supplemented with L. reuteri, S. coelicolor, or their combination. A total of 240-day-old broiler chicks were randomly assigned to four dietary treatments and raised under standard commercial conditions for eight weeks. Liver and intestine samples collected at weeks 4 and 8 were subjected to RNA isolation, sequencing and differential gene expression analysis. Transcriptome profiling revealed unique gene expression patterns associated with each probiotic treatment and organ. Functional enrichment analyses highlighted the modulation of key immune pathways including cytokine signaling and lymphocyte activation, as well as metabolic pathways related to lipid processing and electrolyte balance. Metabolomics revealed that the combination treatment produced the largest unique number of detected metabolites. Together, we demonstrate that the combination of L. reuteri and S. coelicolor induced a synergistic transcriptional and metabolomic response that affects both immune regulation and nutrient metabolism. These findings provide insight into the host-probiotic interaction at the molecular level and support the potential use of targeted probiotics as functional feed additives in poultry.