What Is Enteric Fermentation?

Enteric fermentation is the digestion process of wild and domesticated ruminant animals such as cows, goats, and sheep, and buffalos. Ruminant animals are animals which have four compartments of stomachs, with the largest compartment called rumen. Rumen is responsible for breaking down fibrous plant materials through microbial fermentation. Cellulose is converted into volatile fatty acids (VFAs) which are used by the animals as energy and methane which are released by the animals through burping. Up to 12% of the energy intake of ruminants is lost as methane in this process.

Why Should We Be Concerned?

Globally, ruminant animals are responsible for 30% of total methane emissions. If converted to carbon dioxide equivalent, ruminants produce 2.7 Gt of CO2 annually or about 5.5% of total anthropogenic greenhouse gas emissions. Methane is more short-lived than carbon dioxide, but it doesn’t mean it’s less harmful. Methane traps very large quantities of heat over a period of 100 years, reaching 28 times higher than carbon dioxide. After a decade, most methane reacts with ozone and forms carbon dioxide and water. This carbon dioxide will continue to heat the planet for hundreds or thousands of years. Thus, emitting methane is worse than emitting the same quantity of carbon dioxide, regardless of the time scale.

How Can We Reduce Enteric Methane?

There are several solutions that can be taken by farmers to reduce their livestock emissions:

• Increase feed quality. Opting for cattle feed that has higher contents of dietary oil, such as cottonseed oil, was found to reduce methane emissions by 12%. In addition, milk yield is improved by around 15%.
• Use dietary additives. Adding substances such as seaweed and fatty acids can reduce methane formation in the cow’s rumen. Study showed that the addition of Asparagopsis taxiformis red seaweed can curb methane up to 80%.
• Enhance feed digestibility. Mechanical and chemical pre-treatment such as chopping and alkali treatment makes animal feed easier to digest and potentially reduce methane emissions per unit product by 10-25%.
• Selective breeding. Breed animals that possess genes correlated with lower methane emission can result in up to 17% methane reduction per generation.
• Manage manure. Perform controlled anaerobic digestion of manure and capture methane as energy.

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References:

Baxter, T., & Nicholls, Z. (2020). Climate explained: methane is short-lived in the atmosphere but leaves long-term damage. The Conversation. https://theconversation.com/climate-explained-methane-is-short-lived-in-the-atmosphere-but-leaves-long-term-damage-145040

Farmers Assuring Responsible Management. (n.d.). National Dairy FARM Program How does cow digestion influence GHG emissions? In National Dairy Farm. https://nationaldairyfarm.com/wp-content/uploads/2022/04/Enteric-Emissions-One-Pager_Final-2.pdf

Food and Agriculture Organization. (n.d.). Livestock and enteric methane. FAO. https://www.fao.org/in-action/enteric-methane/background/en

Food and Agriculture Organization. (2025). 3. Options and Strategies. FAO. https://www.fao.org/4/x6116e/x6116e03.htm

World Business Council for Sustainable Development. (2023). Reduce enteric fermentation emissions from ruminant animals - Action Library (EN). The Climate Drive. https://www.theclimatedrive.org/action-library/reduce-enteric-fermentation-emissions-from-ruminant-animals