RESEARCHER: Dr. Ermias Kebreab, UC Davis, 2021


• Feed additives offer a potential method for reducing enteric methane emissions, yet currently dairy farms are not able to receive credit for these types of emission reductions.

• This project produced an expert-led scientific analysis focused on a protocol for quantifying emissions reductions associated with feeding additives for determining carbon offset credits for producers who use methane-reducing feed additives.

• Receiving carbon offset credits for the use of methane-reducing feed additives can provide a potential source of income for the dairy industry, while also benefiting the environment through a reduction in green house gas emissions. 


Microbes in the digestive tract of ruminants produce enteric methane as a byproduct when breaking down and fermenting indigestible plant parts, such as fiber. Reducing the production of enteric methane is an important focus of California dairy farms because enteric methane is a source of greenhouse gas emissions. There are a variety of promising feed additives to reduce enteric methane production. As more research is conducted on these feed additives, it is necessary for the livestock industry to have verified protocols on how to estimate on-farm emissions reductions. 

In California’s carbon offset market, the price of methane is greater than that of carbon (estimated to be between $10 and $50 per ton of CO2 equivalent) because methane is a more potent greenhouse gas. Research on feed additives suggest some may be able to reduce enteric methane emissions by 30 to 80%, with the combination of certain additives being even greater. These reductions equate to a significant amount of potential offset credits for producers. However, dairy producers in California are currently unable to claim any credit if they reduce methane from enteric sources because there is not a protocol in place to quantify this type of carbon offset. 

This project produced an expert-led publication that will be used as the basis for developing a carbon offset protocol. The goal is for agencies to use the information in this paper to develop a protocol for quantifying carbon offset credits for producers who are reducing enteric methane emissions using feed additives. Once these guidelines are established, they can provide more information for producers, researchers, and feed additive companies to develop life cycle assessments to determine the overall carbon-saving ability of different feed additives and their combinations. 

There is great potential for dairy producers to participate in the carbon offset program and receive credits for implementing practices that reduce enteric methane emissions. The development of a protocol to quantify carbon offset credits for producers using feed additives can benefit the dairy industry as a potential source of income while also benefiting the environment by reducing the production of greenhouse gas emissions.