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

Abstract

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.