ARS | Publication request: Effect of nitroethane, dimethyl-2-nitroglutarate and 2-nitro-methyl-propionate on ruminal methane production and hydrogen balance in vitro

Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 11, 2010
Publication Date: April 7, 2010
Citation: Anderson, R.C., Huwe, J.K., Smith, D.J., Stanton, T.B., Krueger, N.A., Callaway, T.R., Edrington, T.S., Harvey, R.B., Nisbet, D.J. 2010. Effect of nitroethane, dimethyl-2-nitroglutarate and 2-nitro-methyl-propionate on ruminal methane production and hydrogen balance in vitro. Bioresource Technology. 101:5345-5349.

Interpretive Summary: Microorganisms within the forestomach of cattle and sheep help digest the feed these animals eat, converting much of the feed to nutrients utilizable by the host. However, some of these stomach bacteria perform an inefficient process, converting some of the feedstuffs into methane, a chemical which is not able to be used by the host animal and thus is subsequently released into the atmosphere. This process of methane production is considered a digestive inefficiency that results in the loss of 2-12% of the host’s gross energy intake and contributes nearly 20% to the United States’ annual emission of this potent greenhouse gas. In earlier studies, we observed that a chemical we have been investigating to kill food-poisoning bacteria in the gut of cattle and sheep also markedly reduces bacterial methane production. Because we were concerned that the earlier tested chemical might be converted to a toxic end product, we synthesized two new less dangerous chemicals and tested these for their ability to inhibit bacterial methane production. We found that both of these chemicals inhibited methane production by more than 90% and that neither had adverse effects on other digestive processes by the bacterial population. These results will help us to develop a feed additive that can inhibit unwanted food-poisoning bacteria in cow and sheep gut while at the same time improving digestion efficiency and helping reduce the United States’ annual emissions of an important greenhouse gas. Ultimately, this research will help farmers and ranchers produce safe and wholesome meat and dairy products at less cost for the American consumer while simultaneously helping the environment.

Technical Abstract: Ruminal methanogenesis is considered a digestive inefficiency that results in the loss of 2-12% of the host’s gross energy intake and contributes nearly 20% to the United States’ annual CH4 emissions. Presently, the effects of the known CH4 inhibitor, nitroethane, and two synthesized nitrocompounds, dimethyl-2-nitroglutarate and 2-nitro-methyl-propionate, on ruminal CH4 production and fermentation were evaluated in vitro. After 24 h incubation at 39oC under 100% CO2, ruminal fluid cultures treated with 2.97 or 11.88 µmol ml-1 of the respective nitrocompounds produced 92% less CH4 (P < 0.05) than non-treated controls. Analysis of amounts fermentation endproducts produced and H2 balance estimates indicate that fermentation efficiencies were not compromised by the nitro-treatments, averaging 76.8, 78.7, 77.4, 80.8, 80.4, 77.4, and 75.1% for control, 2.97 and 11.88 µmol dimethyl-2-nitroglutarate, 2.97 and 11.88 µmol 2-nitro-methyl-propionate, and 2.97 and 11.88 µmol nitroethane, respectively.