Cows fed small amount of seaweed burp 86 per cent less methane in trial Posted 4 updated 4 MarMarch 2021 at 1:41am Cattle methane was reduced by as much as 86 per cent when their diets were subsidised with seaweed. ( Share Print text only Cancel Feeding cattle a small amount of a seaweed species found in Australia has been shown to reduce their methane emissions by up to 86 per cent. Key points: Red seaweed contains a compound that can reduce the production of methane Proponents say it could be the equivalent of removing 100 million cars from the road if adopted by the agriculture industry Some scientists warn the side effects of eating red seaweed on a large scale could include the production of ozone-depleting gas