BREEDING LOW METHANE CATTLE: Genetic trait a game changer for dairy industry

GUELPH — Knowledge is power, and Ontario dairy farmers will soon be empowered to breed low-methane cattle to gradually cut their herd’s emissions of the greenhouse gas 20 to 30 % by 2050, according to Semex.

The bovine semen seller will add a new “methane efficiency” index to its Holstein bull lineup in April, allowing dairy farmers to achieve “a faster conversion to a lower methane herd” by selecting bulls with the desired low-methane trait.

Just as important to the selection process, Lactanet-enrolled farmers will also know the emissions performance of their existing cows, also starting in April, when the milk-recording entity begins giving producers that data. Thanks to a recent breakthrough, Lactanet can tell with 85% accuracy if a cow is a low-methane producer, based on a newly detected signature in that animal’s milk sample.

Methane is touted as a potent greenhouse gas, worse than carbon dioxide, and farm cattle have come under increasing global scrutiny as a methane source. Ruminant animals release methane from both ends of their digestive tract, though mostly (about 90 %) through burping.

Drew Sloan, Semex Vice President of Corporate Development, described methane as a “global enemy” and the identified low-methane trait as a “game changer” for the dairy industry.
Dr. Michael Lohuis, Semex Vice President Research & Innovation, explained that the key breakthrough came when researchers looked at the routine Lactanet milk samples of cows whose methane output was being physically measured at the University of Guelph. Lactanet had recently switched to testing milk with a light-based system — spectroscopy — and the samples from low-methane cows shared “a complex pattern in the mid-part of the spectrum that can be correlated” to the animal’s methane output, Lohuis explained.
That pattern serves as a “proxy trait” that can be reliably used to determine a cow’s methane status from her milk.

So far, over 700,000 first-lactation Lactanet records have been analyzed to predict methane emissions for milk-recorded cows across Canada. “The results showed that you can substantially reduce methane emissions with genetic selection,” Lohuis said.

A low-methane cow is one ranking in the top 16% of the breed for methane efficiency, according to Lohuis. Where the average Holstein produces 1,900 kg of methane annually, her low-methane sister produces about 370 kg less than that.

A farmer would need to breed for the trait through 10 generations to achieve a herd-wide 20 to 30 % reduction in methane emissions by 2050, he said.
“The way genetic selection works, it’s cumulative and it’s additive. You make slow but steady and permanent genetic progress and it just accumulates generation after generation.”

The average drop in methane output per cow could be as much as 420 kg below the average by then.