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Methane emission factors need revision

Methane is a hot topic, but measurement of it is complex and expensive. And are we calculating it in the right way? An international consortium of animal scientists questions this.

Enteric methane (CH4) production from cattle contributes to global greenhouse gas emissions. Measurement of enteric CH4 is complex, expensive, and impractical at large scales; therefore, models are commonly used to predict CH4 production. However, building robust prediction models requires extensive data from animals under different management systems worldwide.

The research looked at data measurements from over 5,200 lactating dairy cows assembled through collaboration of animal scientists from 15 countries. Photo: ANP
The research looked at data measurements from over 5,200 lactating dairy cows assembled through collaboration of animal scientists from 15 countries. Photo: ANP

Data from 5,200 cows

In a new paper, published in Global Change Biology, the researchers conclude that revised methane emission factors for specific regions are required to improve methane emission estimates for dairy cattle in national inventories, as stated on the website of Wageningen UR.

The research looked at data measurements from over 5,200 lactating dairy cows assembled through collaboration of animal scientists from 15 countries (the GLOBAL NETWORK project). This large study showed that methane emission from dairy cattle can be predicted by simplified models requiring readily available feed-related variables. Models requiring only dry matter intake (DMI) or DMI + NDF (neutral detergent fibre) had the second best predictive ability and offer an alternative to complex models. The researchers also address that revised methane emission conversion factors for specific regions are required to improve emission estimates in national inventories.

improve accuracy

The research by the consortium offers opportunities to include region specific methane conversion factors in national inventories. This is essential to improve accuracy of carbon footprint assessment of dairy cattle production systems in several regions worldwide, and to help devise mitigation strategies. The team that conducted the study is currently developing similar databases for predicting and mitigating methane emissions from beef cattle and small ruminants (sheep and goats).

Top 5 articles on All About Feed about mitigating methane through nutrition:

  1. Feed supplement drops methane by 58%
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Source: Wageningen UR and Wiley

6 comments

  • Please note that the French company Valorex has conducted research on this topic with the help of the National Agronomic Research Institute (INRA),
    and has developed a calibration capable of accurately predicting enteric methane emissions from a group of ruminants based on the fatty acid profile of their milk.
    The analysis of this fatty acid profile is done quickly and economically by Near InfraRed Spectroscopy (NIRS).

    The Valorex method is the only one recognized by the UNO to date.

  • Brett Blaikie

    According to the paper I read from University of Illinois the methane production (only North American numbers were calculated) of modern herds and flocks is approximately the same as the bison and passenger pigeons displaced. I would question any process that compromised healthy and efficient outcomes in the name of methane reduction.

  • You're right Brett, in fact, Valorex has also shown that the release of methane is very reduced and feed efficiency improved, when ruminants receive a diet with a balance close to its original diet:
    fresh grass and especially spring grass or alfalfa, compared to the modern diet that most of them now receive in stalls, made from maize and soy...

  • Gayle Somerville

    Over time, methane breaks down into CO2, which is used to grow grass, which the cows eat. This is a cycle, and does not increase CO2 levels, or global warming, unless the number of cows is increasing. Therefore if Brett Blaikie is correct, cows in the US are not an issue, and should be removed from calculations.

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