If things go well in four key areas where work is underway to tackle methane emissions from farm animals they could "make a big hole" in New Zealand's agricultural greenhouse gas emissions, according to Mark Aspin, consortium manager at the Pastoral Greenhouse Gas Consortium.

The Pastoral Greenhouse Gas Consortium is a public-private partnership that has been working for 20 years to reduce agriculture greenhouse gas emissions. Speaking in interest.co.nz's Of Interest podcast, Aspin discusses the lessons and progress along the way.

With the agriculture sector contributing half NZ's emissions, according to the Ministry for the Environment's greenhouse gas inventory, and methane 44% largely due to the digestive process of ruminant animals such as cows and sheep, Aspin talks in detail about the four key methane mitigation tools being worked on.

These are methane inhibitors, genetic selection to breed low-emission cows and sheep, low-emission feed and forage, and a vaccine that could stimulate the animal's immune system to generate antibodies in saliva that target proteins on methane-producing microbes, or methanogens, in the rumen area of the stomach restricting their growth and ability to produce methane.

The Government has a target of reducing biogenic methane emissions from 2017 levels by between 24% and 47% by 2050. Aspin says the four key areas of work have the potential to make a big dent in NZ agriculture's methane emissions.

"In a perfect world yes, we could probably make a big hole in the agricultural emissions if we could get them all to work," says Aspin.

He acknowledges that the vaccine is "proving very tough," but continues to believe it could work.

In the podcast he also talks about the challenges of being a livestock grazing nation, intellectual property related to this technology, regulatory requirements, what's going on overseas, NZ's international climate change commitments, and the position of NZ and its agriculture sector in the context of global greenhouse gas emissions.