Written by Rachel Martin
Cross-border farm trials into the potential of seaweed to reduce emissions in both beef and dairy herds are set to begin in the autumn, Agriland can reveal.
The study will examine the effect of seaweed on rumen fermentation in both beef and dairy cattle and whether its inclusion can suppress methane emissions as a byproduct.
It’s part of a €2 million project led by Teagasc and carried out in collaboration with Queen’s University Belfast, the Agri-Food and Biosciences Institute (AFBI), the Institute of Technology Sligo, as well as institutions in Norway, Sweden, Germany and Canada.
The trials will take place on two of Queen’s University’s ‘partner farms’ and will seek to establish the optimum volume of seaweed to include in a grass silage based ration, while also measuring seaweed’s effect on feed intake, milk production and composition, nutrient digestibility, and nitrogen utilisation efficiency.
The beef aspect of the study will also measure the effect on growth rates, as well as meat quality and composition.
The project will also see different seaweed species screened for their methane-reducing potential to establish if some varieties have more potential than others.
It’s not yet known whether the trials will take place on commercial farms or use herds based at research institutions.
It comes on the back of a lab-based study which finished last year at Queen’s, confirming that including seaweed in livestock diets had the potential to suppress methane emissions from the rumen.
Cow burps
Methane emissions are a major challenge for the industry, particularly as government focus moves towards net-zero emission goals.
In recent years there has been a particular focus on the agricultural sector.
Methane accounts for 23% of Northern Ireland Greenhouse Gas emissions, with 80% of that originating from agriculture.
While there is much debate over how methane should be measured, and whether it should be measured in terms of CO2 equivalent due to its shorter lifespan, it remains the industry’s largest pollutant.
Most of that comes in the form of cow burps. According to the Department of Agriculture, Environment and Rural Affairs Greenhouse Gas Inventory, enteric fermentation (digestion in the rumen) remains NI agriculture’s largest source of GHG emissions, accounting for more CO2 equivalent gases than fertiliser use, manure management and agri-combustion combined.
It’s a similar situation in the Republic of Ireland where methane accounts for almost a fifth of national emissions and 58% of Irish agricultural emissions.
Seaweed studies
There have been some big claims about the potential of seaweed in recent years as a potential solution. One 2016 Australian study claimed including seaweed at 0.2% of Dry Matter Intake (DMI) reduced methane emissions by up to 98% in Brahman-Angus cross steers.
A small-scale experiment carried out in Sligo by seaweed start-up firm Dúlabio last year also found significant potential for seaweed as part of a grass-based diet for beef cattle. It claimed that including seaweed in the diet reduced the number of methane eruptions (or burps) by 79.5% but did not examine the effect on emission volume. The study has not been published in any journals.
However, a trial carried out by Teagasc last year, on pasture-grazing cows, found including seaweed in their ration had no effect in reducing emissions. It did, however, find that including phytochemicals, the active chemical from seaweeds, caused a slight increase in milk solids but did not reduce methane emissions per kilo of solids.
Speaking at a webinar on Friday (April 16), Teagasc researcher Dr. Ben Lahart explained the disparity in results may partly come down to the type of seaweed used.
“It could be due to a number of reasons,” he said. “The indoor experiments are using predominately red sea, within our study we used a very small proportion of that within the supplement.
“Then you have to add into the effect that it was grazing while the others have been indoors, and in that indoor study they were continuously offered the supplement throughout the day, whereas we were offering it twice daily so there are a number of different factors.”
Researchers are hoping to find a locally-grown variety of seaweed that could be effective in reducing emissions. If the crop’s freshness is central to its efficacy importing seaweed could be ineffective.
There have also been suggestions that a synthetic additive could be derived from the most-suited seaweeds.
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