Impact of chitosan supplementation on metabolomic profiles and microbial community dynamics in total mixed ration silage and rumen fluid.

Objective: This study aimed to investigate the effects of varying levels of chitosan supplementation in total mixed ration (TMR) silage on the abundance and dynamics of rumen microbial communities, as well as their associated metabolomic profiles.

Methods: Next-generation sequencing (NGS) and LC/HRMS-based metabolomics were employed to assess alterations in rumen microbiota and metabolites composition in response to chitosan supplementation in TMR silage.

Results: A total of 308 metabolites were identified in TMR silage, 144 of which had a variable importance in projection (VIP) scores greater than 1, marking them as distinguishing metabolites. Notably, chitosan supplementation increased L-valine levels, identifying it as a potential biomarker metabolite. In rumen fluid samples, 33 metabolites were identified, with 13 exhibiting VIP scores over 1, classifiying them as key metabolite indicators. Chitosan supplementation significantly elevated amine compounds, particularly Dibenzylamine and N,N-Bis(2-hydroxyethyl) dodecanamide, in rumen fluid. The primary phyla affected by chitosan in TMR silage were Proteobacteria, Bacteroidota, and Firmicutes. Additionally, the genera Succinivibrionaceae_UCG-002 and Prevotella decreased with chitosan supplementation, whereas Rikenellaceae_RC9_gut_group exhibited increased abundance. Predominantly negative correlations were observed between rumen fluid metabolites (particularly amines and indoles) and microbial populations belonging to Bacteroidota and Firmicutes.

Conclusion: These findings indicate that chitosan supplementation alters rumen metabolic activity and reduced microbial diversity within the rumen.