Plasma non-targeted metabolome of high- and low-body-weight broilers

In large-scale poultry farming, broilers of the same breed share a common genetic background and identical management conditions, yet substantial individual variation in body weight persists. In this study, we identified distinct plasma proteomic profiles between high and low weight broilers, with low weight broilers exhibiting a heightened systemic inflammatory response. The gut microbiome differences between groups were minimal, and fecal microbiota transplantation from high or low weight broilers did not significantly affect body weight. However, lung microbiome analysis revealed that high weight broilers had a significantly higher abundance of Lactobacillus, associated with altered plasma tryptophan metabolism. Aerosolized Lactobacillus rhamnosus, Lactobacillus reuteri, and their combination were administered to modulate the lung microbiota. This intervention significantly enhanced production performance and alleviated LPS-induced systemic inflammation. Aerosolization of Lactobacillus strains elevated metabolites such as L-tryptophan (Trp), indoleacrylic acid (IAA), and indole-3-carboxaldehyde (I3C) in plasma and lung tissues. Mechanistic explorations elucidate that IAA and I3C activated the aryl hydrocarbon receptor (AHR) pathway, promoting nuclear translocation and upregulating SOCS3 expression in macrophages. This inhibited the JAK2/STAT3 signaling pathway, mitigating LPS-induced inflammation. Our findings provide insights into the interaction between poultry production and lung microbiota, establishing Lactobacillus aerosolization as a promising strategy to combat systemic inflammation and improve poultry health and performance.