August 4th, 2015

Let’s get this out of the way first: Cow burps are a real problem.

To get enough nutrition from the plants they survive on, the livestock have evolved a four-compartment stomach that acts as a bioreactor. When a cow eats grass or hay, billions of microbes living in the big, complex organ get to work digesting the partially chewed plants. Through this process of fermentation, otherwise indigestible roughage is broken down into nourishing food for the animal.

But other byproducts of fermentation are methane and carbon dioxide, two gases known to contribute to global warming. The collective belching of all the world’s 1.43 billion beef and dairy cows contributes a significant amount of greenhouse gas to the atmosphere. Livestock, for instance, produce around 25 percent of all methane emissions that come from human activities in the U.S. And the U.N. Food and Agriculture Organization estimates that ruminant livestock digestion produces the equivalent of almost 2.5 billion metric tons of atmospheric carbon dioxide every year.

Now researchers say they are working on an antigas inhibitor that can be put in cow feed to significantly reduce climate-changing burps. Scientists at Pennsylvania State University and Dutch life and materials sciences company DSM have found that an enzyme inhibitor called 3-nitrooxypropanol reduced methane emissions in cows by 30 percent. Learn more below.

Photo: Dairy cow feeding at Shelburne Farms, Vermont. Photo copyright Michael Keller.

They tested their powdered compound supplement on 48 Holstein dairy cows, and it continued to reduce methane formation over the course of 12 weeks. In an additional beneficial side effect, the energy that is normally lost in the ejected gas was used instead by the animal to build mass and produce milk.

The inhibitor “decreased methane emissions from high-producing dairy cows by 30 percent and increased body weight gain without negatively affecting feed intake or milk production and composition,” write the study authors in the journal PNAS. “If adopted, this mitigation practice could lead to a substantial reduction of greenhouse gas emissions from the ruminant livestock sector.”

Study coauthor Alexander Hristov told the Washington Post that 3-nitrooxypropanol appears to work by blocking a step in the metabolic process that produces methane from carbon dioxide and hydrogen. In the study, the group writes that the inhibitor stops the enzymatic process leading to methane formation inside rumen bacteria and archaea.

While the work is promising, scientists not involved in it say more studies need to be done before 3-nitrooxypropanol can be deployed throughout the livestock industry.

Ermias Kebreab, a professor at the University of California, Davis, who studies agricultural greenhouse gas emissions told the Post, “I think it has a real potential to reduce enteric methane emissions. However, before it can be recommended for wide use, the mode of action should be explained well and the long term impact on the animal should be studied.”

Photo copyright Michael Keller.