Can feeding seaweed to cows help fight climate change?

Farmers will soon discover whether seaweed is a superfood that can grow bigger cows and battle climate change.

Researchers in Australia will this summer publish the results of a study on the effect feeding seaweed to cows has on methane emissions (90% of which come from burps).

Previous studies have suggested that mixing seaweed into cow’s feed can reduce their methane emissions by up to 99%.

This could be a huge boost in the battle against climate change: global livestock emissions account for more than a seventh of all man-made greenhouse gas emissions, and methane is considered to be up to 30 times more harmful than carbon dioxide.

Growing bigger cows

Academics at Australia’s James Cook University found that adding just 2% seaweed to dried food can reduce methane emissions by 99%.

However, that research used an artificial cow’s stomach in a laboratory. The only real-life livestock results available to researchers were from a Canadian study that found feeding seaweed cut cow methane emissions by 20%, and studies that showed a 70% reduction in sheep methane emissions when 2% seaweed was added to their diet.

For the past year James Cook University researchers have been feeding cows seaweed at a facility run by Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO).

They are expected to publish their results at the end of July.

As well as cutting emissions, they also hope to show that addition of seaweed can improve the health of cows and help them to grow bigger and stronger.

Methane emissions represent wasted energy, and reducing them could help the cows to be more efficient in processing their feed. This could potentially both help them grow stronger and reduce the amount of feed they need – cutting costs for cattle farmers.

Understandably, the research is attracting interest from farmers, academics and politicians around the world.

In Ireland, MP Michael Fitzmaurice hailed the potential to kickstart a new seaweed industry, while Irish farmers have said they support further investigation of seaweed’s potential to reduce cattle methane emissions.

The Universities of California and Stanford in the US are also reported to be taking seaweed samples from James Cook University to carry out their own tests.

Side effect warning

Despite seaweed’s potential to grow healthier and more environmentally friendly cattle, researchers in New Zealand have warned that there may be some harmful side effects.

Dr Andy Reisinger, the deputy director of the New Zealand Agricultural Greenhouse Gas Research Centre (NZAGRC), looked at the potential of seaweed in reducing livestock emissions with James Cook University six years ago.

They found that the main methane mitigation effects come from the chemical bromoform that is produced in the cow’s stomach when eating the seaweed, rather than the seaweed itself.

This is a problem, Dr Reisinger told NZFarmer, as bromoform has previously been shown to deplete the ozone layer. If cows start emitting bromoform instead of methane, it could result in swapping one environmental problem for another.

There is also limited evidence to suggest major exposure to bromoform may increase the risk of cancer in some animals.