Could selective breeding hold the key to less hot air from the West Vic herd?

What if every new generation of cattle in western Victoria produced less methane than the one before? Researchers argue selective breeding can make that a reality, delivering permanent cuts to emissions in one of the region’s biggest industries.

When a cow breaks down feed in its four-chamber stomach, a small group of microbes called methanogens combine hydrogen and carbon dioxide into methane, which is mostly released when cows burp.

According to non-profit World Animal Protection, cows burp about every 90 seconds. If an example cow sleeps for four hours a day, but still burps when it’s asleep, that is about 1,000 burps a day. 

“Methane traps around 120 times as much heat as carbon dioxide does moment to moment,” said the Massachusetts Institute of Technology.

But after about 12 years, it breaks down and doesn't trap heat anymore, unlike carbon dioxide, which stays in the atmosphere for hundreds to thousands of years.

Curtin University research estimates cattle produce between 50-120kg of methane per cow each year, with diet playing a major role. 

Hydrogen-rich, high-fibre feeds like grass or silage lead to more emissions, while grain or fat-rich diets reduce them, as there is less hydrogen available to be synthesised into methane.

Dairy cows are usually at the higher end of the range, with beef cattle lower.

The Climate Council says agriculture was responsible for more than half of Australia’s methane emissions in 2022-23, nearly 65 percent of which came from cattle.

Farmers and researchers are now pointing to selective breeding as a promising way to bring emissions down. Selective genetic breeding chooses livestock with desirable traits so they become more common in future generations. 

CSIRO research points to scientists using a complex DNA breeding method called genomic selection to pick sires and dams - mothers and fathers - that pass on low-methane tendencies. Because these traits are inherited, the reductions are permanent and build with every generation.

Robert “Macka” McKenzie, a Black Angus farmer from Gloucester in New South Wales, told the Brolga utilising the approach has cut his methane emissions, but also his overall feeding costs on farm.

“We're very focused on genetics to not only reduce our carbon footprint and our methane emissions, but also to add an increase in value per animal,” McKenzie said.

“We purchased a bull in Scotland just lately, that bull is number one in the world for feed efficiency. He eats 3.5kg of dry matter for one kilo of weight gain.”

Through genetics, McKenzie said his animals are now 40kg heavier at weaning than five years ago. 

“They're the things that we've brought together from all around the world to produce an animal that is not just more sustainable, but actually is more profitable.”