Our seaweed is characterised by secondary metabolites with antibacterial properties and demonstrates a potent methane reduction effect in livestock digestive fermentation. At low dose (less than 2%) it reduces methane in cultures by more than 99% and reduces it by >80% in livestock, thereby conserving feed energy in the animal for productive metabolic utilisation and efficient animal growth.
The Asparagopsis species of seaweed produces special substances containing bromine (CHBr3) that prevents the completion of methane construction by reacting with vitamin B12 at the last step, which disrupts the enzymes used by the specific gut microbes that produce high energy methane gas as waste during digestion.
The special properties of seaweed as a feed additive came of interest after a Canadian farmer noticed that cattle in his paddock bounded by the sea were more productive than his other cattle. He discovered that the cattle grew faster, were healthier and easier to manage and then provided it to the rest of his cattle. He was then required to have the seaweed tested by scientists. During the testing it was discovered that greenhouse gas emissions were much lower with the seaweed. Dr Kinley searched the world for a natural way to improve the environment, when he collaborated with JCU they found the ultimate seaweed solution in Australia, it was so effective in reducing GHG he thought the equipment was broken.
Seaweed production globally is booming, with more than 25 million tonnes (measured when wet) farmed each year, which is about double the global commercial production of lemons.
Producing enough Asparagopsis to feed 10% of the almost 1 million feedlot and 1.5 million dairy cattle in Australia would require about 300,000 tonnes a year, and millions of tonnes if it were to be scaled up globally.
With selection and breeding of seaweed varieties for higher bioactivity, this figure could come down, but perhaps only by half, and it would still require large areas of land and water. With typical seaweed production rates at 30-50 tonnes of dry matter per hectare, this suggests that to supply 10% of the Australian livestock industry will require at least 6,000 hectares of seaweed farms.
There are likely to be many indirect benefits, including creating alternative livelihoods in many developing countries where fishing may be in decline, and the use of seaweed as a means to filter detrimental nutrients from rivers or effluent from fish farms.
But seaweed farms more generally will be part of our increasing demands on the marine environment and will need to be part of integrated ecosystem wide management and marine spatial planning.