Fumarate reduces methane production from pasture fermented in continuous culture

This experiment tested the hypothesis that addition of an organic acid (fumarate) would increase the energy captured from a pasture diet during ruminal fermentation. Pasture was fermented with 0, 10, 20, or 30 mM of fumarate constantly infused into four dual-flow continuous culture fermenters. Digestion characteristics responded linearly (P<0.05) as fumarate increased from 0 to 30 mM. Increasing fumarate from 0 to 30 mM reduced (P=0.057) methane production by 38%, and reduced the ratio of acetate:propionate (2.4 v.s. 1.5). Concentrations of propionate and total volatile fatty acids increased by 74% and 19%, respectively. These results were consistent with fumarate acting as an electron-accepting intermediary in the succinate-propionate pathway. The addition of fumarate increased energy capture from a pasture diet by improving the supply of glucogenic compounds and reducing losses to methane emissions.