Integrated Metagenomic and Untargeted Metabolomic Analyses Characterize Enramycin-Associated Colonic Microbial and Metabolic Changes in Weaned Rabbits.

Enramycin is used as a dietary antimicrobial in young animals, but its effects on rabbit colonic ecology remain insufficiently characterized. This study evaluated the effects of enramycin in 60 weaned rabbits randomly assigned to a control or enramycin-treated group (60 mg/kg) for 14 days (n = 30/group). Clinical outcomes were evaluated in all rabbits, whereas paired colonic multi-omics profiling was performed in six randomly selected survivors per group with no recorded diarrhea. Enramycin reduced diarrhea incidence without affecting body-weight development, organ indices, or mortality. Metagenomic analysis revealed unchanged alpha diversity but significant alterations in microbial community structure, including decreased Verrucomicrobiota, Akkermansia, and Alistipes and increased Cyanobacteria and Avigastranaerophilus. Untargeted metabolomics identified 332 features meeting the predefined screening criteria, including 143 upregulated and 189 downregulated metabolites. Prominent pathway annotations included phenylpropanoid biosynthesis and arachidonic acid metabolism. Resistome analysis demonstrated that treatment drove shifts in streptothricin-, aminoglycoside- and glycopeptide-related resistance signatures. The integrated analysis identified associations between four selected genera and the top 30 differential metabolites. Overall, dietary enramycin was associated with a short-term reduction in diarrhea incidence and concurrent changes in selected colonic microbial, metabolic, and resistance gene features. These findings extend enramycin evaluation beyond conventional clinical outcomes and highlight the importance of considering broader ecological effects when assessing dietary antimicrobial exposure in weaned rabbits.