Feeding probiotics-fermented distiller's grains diets increases rumen enzyme activities and glycerophospholipid levels in finishing cattle by modulating rumen microbiota.

BACKGROUND

Distiller's grains (DG), a major by-product of the Chinese Baijiu industry, represent an inexpensive yet high-quality protein raw material. Previous studies have shown that probiotics-fermented distiller's grains (FDG) hold the potential to serve as an effective livestock feed resource. However, the impacts of feeding FDG-based diets on rumen enzyme activities, rumen microbial communities and metabolism in finishing cattle, along with their underlying regulatory mechanisms, remain poorly understood.

RESULTS

After 45 days of feeding FDG diets, rumen enzyme activities increased significantly. Feeding 10% FDG diets increased the relative abundance of the bacterial genus Prevotella_1 and the fungal genera Candida, Mucor, and Scedosporium in the rumen. Conversely, the relative abundances of bacterial genera Veillonellaceae UCG-001 and Candidatus Saccharimonas, as well as fungal genus Talaromyces, were reduced notably in the rumen following FDG diet supplementation. Compared to the FDG-10% group, the FDG-20% group exhibited a higher relative abundance of the beneficial bacterial genus Bifidobacterium and the fungal genus Plectosphaerella. Non-targeted metabolomic analysis indicated that the differential metabolites were primarily categorized as benzenoids, lipids and lipid-like molecules, and organic acids and derivatives, which were significantly enriched in the neuroactive ligand-receptor interaction and taste transduction metabolic pathways. Untargeted lipidomic analysis further demonstrated that feeding 20% FDG diets elevated the levels of glycerophospholipids in the rumen. Spearman analysis identified the correlations between specific bacterial and fungal genera and rumen enzyme activities, differential metabolites, and lipids.

CONCLUSIONS

These results suggest that feeding FDG diets potentially improves rumen enzyme activities and up-regulates the levels of glycerophospholipids in the rumen, which may be associated with the alterations in specific rumen microbiota involved in degrading cellulose. Of these, 20% FDG replacement emerges as a better dose within the range of FDG additions in this study. Video Abstract.