For Stakeholders

New Methodology for the Reduction of Enteric Methane Emissions Open for Public Comment

If a carbon offset project developers finds that no existing methodology meets their needs, VCS offers them the opportunity to develop a new methodology that does, or to revise an existing VCS methodology. The below methodology is open for public comment until 30 March 2019. Comments submitted during this time will become part of the public record and will also be considered by the validation and verification bodies and the developer.


Ruminants like cattle, sheep, and goats release methane as a result of their digestion process as part of which bacteria, protozoa, and fungi contained in the fore-stomach of the animal (rumen), ferment and break down the plant biomass eaten by the animal. This process, called enteric fermentation, is the largest source of global emissions from ruminant supply chains, contributing about 58% percent of the whole sector.1 To mitigate the increasing emissions impact of cattle products, strategies aimed at reducing the emission intensity of this sector are needed.

This new methodology is based on a deeper understanding of the biochemical processes in the rumen and of methanogens (the microorganisms within the rumen that produce the methane) which have led manufacturers to produce natural feed supplements that inhibit methanogenic activity and thus reduce methane emissions. Such supplements are safe for the animal and aim to significantly reduce methane emissions.

This methodology provides the equations and parameters for calculating the emission reductions produced through the use of methanogen-inhibiting feed supplements. For ease of use it uses emission reduction factors, eliminating the need for direct measurement for monitoring. In addition, it is globally applicable and utilizes an activity method for the demonstration of additionality.

The full draft of the Methodology for the Reduction of Enteric Methane Emissions from Ruminants through the Use of 100% Natural Feed Supplement is on our website for review. Please send any comments to by 30 March 2019.

1 FAO Global Livestock Environmental Assessment Model (GLEAM) public database.

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