We often hear about carbon dioxide as a ‘greenhouse gas’ that helps to warm the Earth’s atmosphere, but there are other duvet gases too. They include methane, a gas that is belched out of some livestock (ruminants) such as cattle and sheep.

With more than 6.5 million head of cattle in Ireland, that potentially constitutes a considerable amount of methane. The Vistamilk SFI Research Centre, co-funded by the Department of Agriculture Food and the Marine, with its headquarters in Cork, is looking at ways to reduce those greenhouse-gassy belches.

One approach, led by Dr Sinead McParland at Teagasc, is to analyse the milk that dairy cows produce to figure out what is happening in one of the cow’s stomachs, or rumen. By looking at the fatty acids in the milk, she can build up a picture of activity in the rumen and potentially identify cows that naturally belch less methane as the microorganisms in their stomachs digest food.

This offers a potentially non-invasive way of tracking a cow’s methane production, and by looking back at the records to identifying bulls that sired those cows, the hope is broaden the current breeding programmes to generate methane-light cattle into the future.

Another strategy to cut the methane emissions from livestock is to give them food that does not encourage the microorganisms in their stomachs to produce the gas. Cows in Ireland predominantly eat grass, which lends their meat and milk a desired richness, while also being low cost and environmentally friendly. Dr Laurence Shalloo, Deputy-Director of Vistamilk, leads a programme to examine how tweaking the diet of cows can affect their methane emissions.

But how can you measure how much methane a cow produces? Vistamilk‘s approach is to place measuring equipment in fields where cows graze and incentivise the cows to the machines and encourage them to stay at the machines for periods of up to four minutes.

“While the cows are eating, the machine can measure the methane content of their breath,” says Dr Shalloo. “We are giving the cows particular complementary feeds in their diet, and the machines will tell us how that affects the methane-content of their belches over time.”

In the past, some studies have shown that the effects of methane-reducing complementary feeds in the diet can wear off over time, but Dr Shalloo at Teagasc is encouraged by recent developments in the field. “The new generation of feeds and additives being tested now are showing much more promise, with bigger effects and in many cases the effects persist over time,” he says. “We will need to ensure that any changes to the diet have positive and lasting effects, and that is why the research is needed.”

At Teagasc and at APC Microbiome Ireland SFI Research Centre, Professor Catherine Stanton is looking at how adding naturally occurring microbes called lactic acid bacteria to the diets of cows and sheep can affect methane emissions. The project is called METHLAB and it is funded by FACCE ERA-GAS, an EU ERA-NET Cofund programme for Monitoring and Mitigation of Greenhouse Gases from Agri- and Silvi-culture, coordinated by Teagasc.

“Lactic acid bacteria occur naturally in the intestines of cows and sheep, and they are also widely used in industry and they can be produced economically in large quantities,” says Professor Stanton, who leads the project with researchers in Cork, The Netherlands, France, Italy and New Zealand. “We are examining how they can be implemented to naturally influence the microbes in the rumen of cows and sheep to mitigate methane and create a more sustainable, emission-efficient food production system.”

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