The term is a bit abstract and Latinate which is ironic in light of what it represents — the gas that comes from cows, sheep and other animals that chew grass to eat.  Certain animals are called ruminant because they have a “rumen” or large stomach that allows their digestive system to process the plant materials the animals eat.  “Fermentation” is a chemical breakdown and “enteric” means ‘relating to or occurring in the intestines.’  Since cows and sheep are able to digest grass and other plant materials their food source can be cheap to produce and such conditions serve as the basis for Ireland’s grass-fed farming system.

Unfortunately the gas that is produced and emitted by the cows and sheep is methane that is a very strong greenhouse gas that contributes to global climate change.  Globally, ruminant livestock produce about 80 million metric tons of methane annually, and an adult cow can emit 80-110 kgs of methane.  The methane from animals is a large part of the GHG emissions from the agricultural sectors in the Republic of Ireland and Northern Ireland.

Experiments are being undertaken to see if changing the diet of the animals, by adding materials to the grass or to the animals, can reduce the level of methane generated, and at the same time improve the productivity of the animals.

Some further ideas to explore on Enteric Fermentation:

Determine how the methane gas emitted from cows and sheep is measured.

How can the diet be changed to reduce the levels of methane generated?

If one solution to rising levels of GHGs is a carbon tax, would that reduce the levels of methane from farm animals?


“Enteric Fermentation Mitigation,” Pew Center on Global Climate Change.

“Ruminant Livestock,” United States Environmental Protection Agency.

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