Butyrate Supplementation Affects Mrna Abundance of Genes Involved in Glycolysis, Oxidative Phosphorylation and Lipogenesis in the Rumen Epithelium of Holstein Dairy Cows

Energy availability in epithelial cells is a crucial link for maintaining epithelial barrier integrity; energy depletion is linked to impaired barrier function in several epithelia. This study aimed to elucidate the effects of exogenous butyrate on mRNA abundance of genes indirectly involved in rumen epithelial barrier integrity. Sixteen mid-lactation Holstein cows fed a total mixed ration received a concentrate mix to induce Subacute Ruminal Acidosis (SARA). For 7 days, while being fed the concentrate mix, cows were assigned either a control treatment or a butyrate treatment, in which cows were fed butyrate at 2.5% daily dry matter intake in the form of a calcium salt. On days 6 and 7, rumen pH was measured continuously and on day 7, rumen biopsies took place. Rumen pH fell below 5.6 for more than 3 hours per day in both treatments, con-firming the occurrence of SARA. Microarray and pathway analysis, confirmed by real time PCR, showed that exogenous butyrate significantly increased the mRNA abundance of hexokinase 2 (fold change: 2.07), pyruvate kinase (1.19), cytochrome B-complex 3 (1.18) and ATP Synthase, F0 subunit (1.66), which en-code important glycolytic enzymes. Meanwhile, butyrate decreased mRNA abundance of pyruvate dehydrogenase kinase 2(-2.38), ATP citrate lyase (-2.00) and mitochondrial CoA transporter (-2.27), which en-code enzymes involved in lipogenesis. These data suggest exogenous butyrate induces a shift towards energy mobilization in the rumen epithelium, which may aid barrier function in the rumen epithelium during SARA.