The sheer amount of research that is going on into reducing greenhouse gas emissions from ruminant livestock was evident at a conference at Queen’s University Belfast (QUB) on Monday.

In particular, QUB is leading a new a global research alliance which is aiming to develop better understanding about the precise makeup of rumen microbes.

These are tiny life forms, such as fungi, bacteria and archaea which are present in the largest stomach of cattle and sheep.

The microbes have a crucial role in the digestive process by breaking down plant material, although this process leads to the production of methane, a potent greenhouse gas.

“Farmers don’t feed cows or sheep or goats. They feed microbes. It is the microbes that make nutrients available for the animals,” said Dr David Yáñez-Ruiz from the Spanish Research Council.

Professor Sharon Huws from QUB said the new global research alliance is aiming to grow rumen microbes in isolation so that scientists can learn exactly how they work.

“If you don’t drill down to this level, then it really is quite difficult to get innovations coming through,” she said.

Feed additives

At present, the most advanced technology for supressing methane emissions is Bovaer, a feed supplement which has an active ingredient known as 3-NOP. Various trials have found it can cut emissions by around 30% on average.

Other research findings were presented on Monday which showed the feed additive RumenGlas reduced methane by 17% to 28% and another product, SilvAir, cut emissions by around 10%.

Despite these promising results, researchers want to keep developing more products to suppress methane emissions from livestock.

Huws said a long-term concern is that rumen microbes will adapt and become resistant to feed additives, so the products could become less effective over time.

“It’s about having a toolbox so, if adaptation comes, then the next generation is ready,” she said.

Another focus of research involves making feed additives more suitable to farming systems that are not based around feeding total mixed rations.

Dr Sinéad Waters from Teagasc highlighted trials carried out at Moorepark, Co Cork where Bovaer was offered to grazing cows twice a day at milking.

“Methane was reduced by 40% initially, then up to 30% right up to 2.5 hours, but by three hours it was quite limited. Over the course of the day, it led to an overall reduction of 7%,” she said.

Other options

Other methane-suppressing feed additives are under development, although getting products that work at a farm level appears to be far from straightforward.

Additives containing red seaweed have been shown to cut emissions by over 20% in certain trials, but Waters highlighted a range of practical issues with its use.

“It is really impractical for transport, it is not native to Ireland, there is a lack of consistency and it’s very expensive,” she said.

Brown seaweed is widely available in Ireland, although Waters described the results of trials by Teagasc which used it as a feed supplement as “disappointing”.

Some existing feed ingredients can suppress methane emissions. These supplements could be particularly advantageous because they do not require a lengthy regulatory approval process.

For example, trials have shown linseed oil can cut methane emissions by 18%. The downside is it also reduced feed intakes by 5% and linseed oil is costly at around €2,500 per tonne.

Rapeseed-based products are much cheaper, and Teagasc trials have shown no impact on feed intakes, although methane emissions had a smaller reduction of around 8%.

“Future priorities include the potential for synergies by combing feed additives. Slow release and bolus technology for use in grazing systems is a really big priority for us,” Waters said..

Vaccines and breeding for low emission ruminants

The roll out of an injectable vaccine that leads to a long-term suppression of methane production in livestock would be a major breakthrough in addressing agricultural emissions.

However, speaking in Belfast on Monday, Dr David Yáñez-Ruiz from the Spanish Research Council suggested the development of a methane vaccine remains a long way off.

For the technology to work, it would require the animal’s immune system to be stimulated to produce antibodies which suppress the microbes in the rumen that produce methane.

Yáñez-Ruiz described the range of microbes within the rumen as “a black box” which works in a different way to all parts of a ruminant animal.

“It is a huge and diverse ecosystem, and we don’t really know how it is controlled. That explains why it is so complex and so challenging to develop a vaccine,” he said.


Looking at the potential of genetics, Dr Ross Evans from the Irish Cattle Breeding Federation (ICBF) said methane production is a heritable trait, so it is possible to breed for lower emission animals.

He said previous research suggests methane production has a heritability value of 0.05 to 0.29. This was described as “low to moderate” although Evans pointed out the trait is more heritable than fertility.

Professor Mike Coffey from Scotland’s Rural College said genetic improvement in the UK dairy sector over the past 20 years has seen methane emissions per litre of milk reduce by around 1% per year.

“Not everything is rosey in the garden though. Things are not optimal because cows have been getting bigger,” he said.

Coffey explained that liveweight correlates to both feed intake and methane emissions.

“We can reduce emissions now because cow size is a highly heritable trait which can be reduced rather quickly,” he said.

Climate change is not a priority for consumers

The key issues that are important for consumers have changed as the cost of food has increased, according to an annual survey carried out by supermarket chain Morrisons.

“The response ‘selling affordable food’ has knocked ‘safe food’ off the top spot for the first time,” Emma Nelson from Morrisons told the conference in Belfast.

She said climate change is rising in importance among survey respondents but still ranks far down the list of consumer priorities in 15th position.

The findings suggest that consumers are unlikely to pay a premium for meat and dairy products with lower emissions.

“If we put extra costs on the shelf, people will drop out of the meat and dairy categories,” Nelson maintained.

If a price premium is not available, it raises questions about what incentive will farmers have to reduce emissions, especially if it means extra costs with buying feed additives or changing breeding strategies.

Professor Mike Coffey from Scotland’s Rural College argued that the criteria to qualify for farm support payments could be a key driver in the future.

This is already being seen in NI to an extent where new suckler and beef headage payments are being linked to calving interval, age of first calving, and slaughter age.

“An added incentive from the government may well be a withdrawal of subsidies to target more change. Change is coming, it’s just a question of how fast it comes,” Coffey said.