Livestock is estimated to be responsible for up to 14% of all greenhouse emissions from human activities. Besides carbon dioxide, farming generates two gases in large quantities: nitrous oxide from fertilizers and methane.
Methane is primarily belched out by cattle and sheep as part of their normal digestive processes and accounts for more than a third of total emissions from agriculture. Ruminant livestock (cattle, sheep, buffalo, goats, deer, and camels) have a fore-stomach containing microbes called methanogens that digest coarse plant material and produce methane as a by-product. The average ruminant produces 250 to 500 liters of methane a day.
Such direct emissions account for about 70% of greenhouse gas emissions by the agricultural sector in Australia. This makes livestock the third-largest source of greenhouse gas emissions after the energy and transport sectors. Livestock is the dominant source of methane and nitrous oxide, accounting for 56% and 73%, respectively, of the country’s emissions.
Farmers are feeding their cattle a range of supplements to test whether they can cut methane emissions. The supplements include oils, fats, tannins, probiotics, nitrates, enzymes, marine algae, and Australian native vegetation.
Two Australian companies, CH4 Global and Sea Forest, kicked off commercial trials this month of a feed supplement that they say can enable the livestock to become carbon neutral. The feed additive is made from the asparagopsis seaweed species, which reduces livestock emissions by more than 80%. Australia’s red meat industry has committed to achieving net-zero emissions by 2030.
In neighboring New Zealand, the farming science research institute AgResearch is testing vaccines on livestock that can act against certain gut microbes responsible for producing methane. It is also developing genetically modified ryegrass that has been shown to reduce methane emissions in livestock.