By the time a newly begun trial in the Waikato is complete farmers hope to know which breed of bull burps less.
The trial, aimed at seeing if there is a link between cows' genetics and how much methane they produce, could be a gamechanger in the fight against climate change.
Nearly half of the country's greenhouse gas emissions come from agriculture, according to the Ministry for the Environment. The main source of agriculture emissions is methane from livestock digestive systems, which makes up almost three quarters of agriculture emissions.
But according to scientists at Livestock Improvement Corporation (LIC) and CRV Ambreed, those agricultural methane emissions could be reduced if the new trial is successful.
Richard Spelman, LIC's chief scientist, told The Project if all goes well they could get a five to 10 percent reduction in methane emissions from cows by 2050.
"The aspect that we've got here is that genetics is cumulative and permanent - so what we do this year gets built upon in future years," he said.
Between them, LIC and CRV sire 90 percent of the country's dairy herd through their artificial breeding bulls.
New Zealand currently has two predominant parent breeds, Jersey and Holstein Friesian, says Spelman.
"Through this trial we'll find out if either of the two breeds are better than the other one," he said.
"What we're doing is putting the animals in a pen, usually for about two to three weeks, and we measure how much they eat and also how much methane they express through their breath."
Spelman said making genetic changes would have a far greater impact than merely changing the animals' diet.
"It's important that we have animals that continue to produce a lot of milk for New Zealand, so feeding them less or slower doesn't really make sense - we've got to have animals that really are far more efficient in their milk production per methane emission."
Andy Medley, operations manager at CRV, said a reduction in methane emissions would not just help the country become greener overall, but would also be good for farmers.
"If farmers can reduce our overall methane emissions in the herd it's a really cost-effective solution for them - they've got to get their cows in calf every year and it's exactly what they've got to do year on year," he told The Project.
"We're all consumers in this discussion and argument. We've got a solution here and farmers need to be recognised that we've got a positive way of addressing those issues that are out there for everyone."
The trial, which began this week, is currently in its first phase. After measuring the amount of methane produced by a small number of bulls, the second phase will get underway in February 2021. At that time scientists will aim to identify individual bulls that produce less methane and potentially breed a lower methane-emitting cow.