Mechanisms of Volatile Fatty Acid Absorption and Metabolism and Maintenance of a Stable Rumen Environment

As a primary energy source for ruminants, volatile fatty acids (VFA) have been estimated to provide up to 75% of the total metabolizable energy (Bergman, 1990). Thus, it is not surprising that diets promoting fermentation and greater production of VFA also promote greater levels of productivity (e.g. milk production) than less fermentable diets (Kolver and de Veth, 2002; Oba and Allen, 2003a,b). However, as a weak acid, VFA will dissociate in the rumen releasing a proton thereby decreasing ruminal pH under most circumstances. Thus, when production of VFA exceeds the ability to neutralize the protons, ruminal pH decreases and ruminal acidosis can occur.