||"The principal VFA [volatile fatty acids] in either the rumen or large intestine are acetate, propionate, and butyrate and are produced in a ratio varying from approximately 75:15:10 to 40:40:20. Absorption of VFA at their site of production is rapid, and large quantities are metabolized by the ruminal or large intestinal epithelium before reaching the portal blood...In all mammals examined, the
anion form of acetic acid, or acetate, is the main VFA
present. In fact, acetate usually is present in higher
concentrations than all other organic anions combined.
Propionate and butyrate also are present in large concentrations,
although their amounts can vary considerably
with diet. Commonly, molar ratios of acetate to
propionate to butyrate are found to vary from
~75:15:10 to 40:40:20."