Effects of Adding Butyrate or Exogenous Fibrolytic Enzymes on Ruminal Epithelium, Metabolism, and Microbiota of Beef Cattle

Feedlot cattle produce high concentrations of short-chain fatty acids (SCFAs) through ruminal fermentation, with butyrate playing a crucial role in epithelial development and SCFA absorption. This study evaluated the effects of dietary sodium butyrate or exogenous fibrolytic enzymes on the ruminal epithelium and microbiota. Three rumen-cannulated Aberdeen Angus steers were assigned to a replicated 3 × 3 Latin square design, totaling six experimental periods. Each period lasted 28 d, comprising 14 d of adaptation and 14 d of finishing. Diets only differed in additive inclusion: CON-control; ENZ-exogenous enzyme complex (0.01% of the dry matter [DM]); BUT-sodium butyrate (0.3% DM during adaptation; 0.1% during finishing). The ENZ reduced the ruminal temperature (<i>p</i> = 0.04), and Diplodinium population (<i>p</i> = 0.03). The CON animals had greater lipopolysaccharide-binding protein concentration (<i>p</i> = 0.02). No treatment effects were observed for the alpha and beta diversity of bacterial communities, but shifts in abundance at the phylum level were detected for Bacteroidetes, Firmicutes, and Proteobacteria. Papillae dimensions were not significantly altered by treatments (<i>p</i> > 0.05). These findings suggest that while BUT and ENZ have some influence on the ruminal environment, their effects at the tested doses were limited, indicating the need for further studies with varying doses or combinations.