Australian scientists have started the first trial in feedlot cattle of a seaweed proven to cut methane emissions from ruminants, Rob Kinley, a researcher at James Cook University, told the Irish Farmers Journal.

Earlier research published last year showed that feeding a small amount of the red tropical seaweed Asparagopsis taxiformis reduced methane emissions from sheep by up to 80%, and 100% from cattle rumen samples reproducing the digestion process in a lab environment. Methane is a potent greenhouse gas known to contribute to global warming.

“No changes in liveweight gain were identified” in sheep, the researchers found, adding that “further work is required to define the long-term effects on productivity and animal health”. Ways of feeding seaweed to livestock out at grass economically would also need to be developed before the research could apply to typical Irish grass-based systems.

A cousin of the seaweed used in Australia, Asparagopsis armata, grows in temperate waters. Galway-based firm Ocean Harvest previously grew it on a small scale. “This is something we are considering, given the information coming out of Australia,” a company representative said.

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Seaweed shows promise to cut methane emissions

Experiments in vitro and in sheep have shown the ability of certain seaweeds to reduce greenhouse gas emissions from cattle and sheep, and tests are now under way in live cattle.