Effect of fumaric acid in combination with Asparagopsis taxiformis or nitrate on in vitro gas production, pH, and redox potential

Reduction in enteric methane (CH4) emissions from cattle can be achieved through use of feed additives, which often results increased emission hydrogen (H2). The objective this study was to investigate vitro effects a known sink, fumaric acid, combination with either 2 inhibitors, the macroalga Asparagopsis taxiformis or nitrate, on CH4 and H2 production, degradability, pH, redox potential. A corn silage (0.5 g; control) incubated buffered rumen fluid addition 0.025 g nitrate (Nit), dried A. (Asp), + acid (Nit+Fum), (Asp+Fum). Accumulated gas production determined using AnkomRF system equipped airtight gasbags. There were 9 replicates per treatment 3 stopped after 24, 36, 48 h incubation. amount undegraded by filtration. Gas composition chromatography. Degradable dry matter, degradable organic potential, data analyzed mixed model. Asp Asp+Fum reduced 98% greater at all incubation times, whereas Nit Nit+Fum (mL CH4/g matter) 52% 63% compared control. Hydrogen only detectable treatments, no difference between treatments. treatments had minor potential fermented fluid, pH lowest for including taxiformis. In conclusion, both production. Fumaric did not reduce result any levels H2. Future dose-response studies will contribute investigating as sink during mitigation.