Multi-omics elucidates the regulatory mechanisms of tryptophan in gut health of weaned piglets.

Tryptophan (Trp), an essential amino acid (AA) implicated in diverse physiological and pathological processes, remains incompletely characterized in its mechanisms regulating intestinal health in weaned piglets. In this study, 27 weaned Bama miniature pigs with highly homogeneous genetic characteristics (6.200 ± 0.242 kg) were randomly divided into three groups and fed a basal diet, a diet supplemented with 0.5-fold Trp, or a diet supplemented with 1.5-fold Trp for 21 days. We used multi-omics approaches to investigate the mechanisms by which Trp regulates intestinal health through dietary interventions with different concentrations. Both Trp-supplemented groups exhibited significantly reduced diarrhea incidence (P = 0.012) and improved intestinal morphology compared to the control group (P < 0.05). While Trp-targeted metabolomics showed no statistically significant alterations, metagenomic analysis revealed Trp-driven microbial remodeling, characterized by increased α-diversity, elevated abundances of Deferribacteres, Turicibacter, Clostridials_Bacteria, and Turicibacter_Sanguinis, alongside decreased Tenericutes and Chryseobacterium. Transcriptome analysis further identified immune-related pathways as central targets of Trp action. Subsequent cytokine quantification confirmed Trp's immunomodulatory effects: pro-inflammatory cytokines (IL-1β, IL-6, IL-17) decreased, while anti-inflammatory IL-10 increased. Collectively, our findings demonstrate that Trp alleviates weaning-associated intestinal dysfunction by reshaping microbial ecosystems and regulating immune homeostasis.