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º¬Ðß²ÝÉçÇø is one of a range of organisations up and down the UK who form part of the UK Dairy Carbon Network.

With around 40 to 50 per cent of a farm’s carbon footprint coming from methane, tackling emissions is crucial if we are serious about reducing dairy’s environmental impact.

However, methane is notoriously difficult to measure under commercial farm conditions.

Yet without accurate, on-farm data, it is hard to know if strategies to reduce it are truly effective. The UK Dairy Carbon Network aims to address this challenge by not only exploring ways to measure methane but also implementing proven ways to reduce greenhouse gases (GHG) emissions onto farms.

In this piece - also published by the UK Dairy Carbon Network - Liam Sinclair, Professor of Animal Science at º¬Ðß²ÝÉçÇø and lead academic partner for the Midlands Farm Network explains how GreenFeed units can help facilitate this issue.

What are GreenFeed units?

GreenFeed units are specialised tools designed to measure methane output from cows in both housed and grazing environments. Each unit operates much like an out-of-parlour feeder. It offers a small amount of “bait feed” – around 300 to 400 grams – to encourage cows to place their heads into the device.

While the cow eats, the unit measures the methane she exhales. Because around 95 per cent of methane is released through belching from rumen fermentation, this method provides a very accurate estimate of total emissions. With cows visiting the unit 20-30 times over 10 to 20 days, we can collect robust, individualised data.

Typically, cows produce between 350-450 grams of methane daily. By using GreenFeed units, we can assess how cows respond to dietary variations, forage quality improvements or other feed formulation changes to give us real-world data instead of relying on book values.

How accurate is it?

The gold standard for measuring methane is the use of respiration chambers, sealed rooms where every gas going in and out is precisely monitored. However, these are impractical for everyday use on commercial farms. Cows in chambers aren’t in their natural environment, and the set-up is expensive and restrictive.

GreenFeed units, on the other hand, offer a practical, portable, and internationally-recognised alternative. We can move them between paddocks for grazing herds or use them indoors. They provide high-quality data in real-world farming conditions.

Alternatives under evaluation

As part of the UK Dairy Carbon Network project, we’re also assessing alternative methods such as ‘sniffers’ for spot sampling and prediction equations based on milk output. These are quicker but less accurate and don’t measure airflow, which is crucial for calculating total emissions. We aim to compare these tools to GreenFeed units to identify a balance between precision and practicality.

Role in the UK Dairy Carbon Network

GreenFeed units are central to our work on the project.

In addition to controlled studies here at Harper Adams, Reading, and AFBI in Northern Ireland, we’re deploying units on commercial farms. This allows us to measure actual methane outputs under real-life conditions, something most carbon calculators cannot yet do accurately.

Carbon calculators often use generic prediction models that may not best reflect management, herd, or feeding systems. This means changes farmers make, whether in feeding, fertility, or youngstock management, may not be recognised.

Our goal is to close that gap.

By collecting and analysing methane data directly from a herd, we can offer a much more accurate picture of a farm’s emissions. This in turn supports more targeted and effective reduction strategies.

Looking ahead

Ultimately, we aim to simplify methane monitoring. While GreenFeed units are currently the best available tool, we’re working toward more scalable, cost-effective systems that can still detect meaningful changes.

For now, collecting data is key. The more we understand how methane output responds to different diets, breeds, and systems, the better we can equip the UK dairy industry to meet its environmental goals.