Research carried out by Teagasc has found that methane emissions from Irish dairy cows are being over-estimated by 9%, according to Dr Hazel Costigan.

The post-doctoral researcher is currently working on identifying different methane-reducing feed additives for grazing dairy cows.

“When a country doesn’t have enough of their own data, they have to use an internationally-derived methane conversion factor. Based on some of the research we have done, our methane is being over-estimated. The methane conversion factors vary greatly across the year. They are particularly much lower in spring time and they are about 9% lower across the year.

“What we are trying to do is refine these methane conversion factors so that they are more applicable to grazing dairy cows, their genetic makeup and the forage they’re consuming,” Costigan said.

The main focus of the research being carried out, Costigan said, is to find a feed additive that is compatible with Irish grazing systems, while at the same time not affecting animal performance or food safety.

A number of studies have been carried out in Moorepark, with feed additives being fed in the parlour through a total mixed ration (TMR) diet and in minerals before shaking on silage.

The inhibitor 3-NOP has proven to reduce enteric methane by 22% when fed as part of a TMR.

Some 3,500 cows across 18 of the Teagasc Signpost dairy farms used the additive last winter.

Research will continue to look into the efficacy of other feed additives, Costigan said, alongside ensuring that they’re practical for feeding on commercial farms.