The CSIRO has identified a strain of seaweed that can reduce bovine methane emissions by more than 99 percent if added to cow feed in small amounts.

Methane is a greenhouse gas 28 times more powerful than carbon dioxide. When cows burp out methane, as much as 15% of the energy in their feedstock is being thrown away instead of converted into meat. For more than a decade, researchers have been aware that adding seaweed to a cow’s diet made a significant reduction to that methane release, leading to better meat production as well as reduced greenhouse gas emissions.

Early tests found seaweeds that could cut methane release by up to 20%. CSIRO scientists have now re-run the tests with a variety of different species of seaweed to find out which is the most effective.

One species, Asparagopsis taxiformis, which grows in the tropical waters off Queensland, was found to reduce methane production by more than 99%. Even in low doses, this particular seaweed species appears to almost totally disrupt the action of gut enzymes that produce the methane.

The CSIRO estimates that it would require about 600 square kilometres of seaweed farms to produce enough to give an effective daily dose to all of the 2.5 million cows in Australia alone.