Gut-Derived <i>Lactobacillus rhamnosus</i> GG Alleviates Intestinal Inflammation in Laying Hens via Microbiota Remodeling and Tryptophan Metabolic Reprogramming

Intestinal inflammation compromises nutrient absorption, health, and productivity in laying hens. Here, we isolated a gut-resident <i>Lactobacillus rhamnosus</i> GG (LGG) strain from indigenous chickens and evaluated its prophylactic effects against dextran sulfate sodium (DSS)-induced intestinal inflammation. Oral LGG administration improved growth performance and antioxidant capacity, restored the villus structure, and reinforced epithelial barrier integrity by upregulating tight junction genes. LGG markedly reduced pro-inflammatory cytokines (<i>IL</i>-1β, <i>IFN</i>-γ) and increased <i>TGF</i>-β. 16S rRNA sequencing showed that LGG normalized microbial diversity, corrected the Firmicutes/Bacteroidetes ratio, enriched beneficial taxa (<i>Lactobacillus</i>, <i>Lachnoclostridium</i>), and reduced inflammation-associated genera (<i>Escherichia</i>, <i>Bacteroides</i>). Untargeted metabolomics revealed a significant modulation of tryptophan metabolism, including elevated levels of kynurenic acid, xanthurenic acid, and indoleglyoxylic acid. The microbiota-metabolite correlations indicate a coordinated regulatory axis underlying LGG-mediated protection. These findings demonstrate that native LGG mitigates intestinal inflammation through microbiota remodeling and metabolic reprogramming, supporting its potential as an antibiotic-free strategy for improving gut health in poultry.