Temporal metabolomic fingerprinting identifies adenine as a novel biomarker for early detection of Escherichia coli infection in broiler chickens.

Avian pathogenic Escherichia coli causes septicemia in broiler chickens leading to high mortality and economic losses. Current diagnostic methods, such as serology and culture, cannot detect infections during early asymptomatic stages. Hence, this study focused on identifying novel serum metabolic biomarkers and pathways as an early detection prediction tool. Ross broiler chicks were challenged with E. coli at 3 or 5 d of age, and blood samples collected at 8 and 24 h following infection. Serum samples were analyzed for metabolite alterations using targeted The Metabolomics Innovation Centre (TMIC) mega metabolomics assay. Data was processed through comprehensive statistical analyses, including univariate, multivariate, and meta-analysis approaches. At 8 h post-infection, top metabolites like adenine, N-acetyl-alanine, N-acetyl-soleucine, N-acetyl-valine, and orotic acid related to nucleotide and amino acid metabolisms were downregulated (p = < 0.05). At 24 h, a distinct metabolic shift emerged with hippuric acid increasing, while adenine showed further depletion, accompanied by decreases in N1-acetylspermidine, N-acetylputrescine, and a modest increase in picolinic acid related to nucleotide, polyamine and immune response pathways (p = < 0.05). Correlation metabolite networks show that at 8 h post-infection, broiler chicken showed enhanced metabolic coordination, while at 24 h, disruptions in polyamine, nucleoside, and fatty acid pathways reflected systemic rewiring. The progressive depletion of adenine at both 8 and 24 h post-infection supports it as a novel metabolite signature for E. coli infection.