Deputy Prime Minister Barnaby Joyce said in exchange for supporting the net-zero plan, the Nationals ensured export emissions and agriculture methane would not count towards the overall target.

"What that would spell for the Australian beef industry, for the feed-lot industry, for the dairy industry, would be a disaster," Mr Joyce said.

"The Nats were absolutely implicit that no deal would go forward that we would support unless it was absolutely categorically ruled out, and we got that."

However, reduced livestock methane emissions will be key to achieving net-zero, according to the government's official roadmap.

"A major focus is identifying technological solutions for reducing methane emissions from livestock," the plan states.

In Question Time on Wednesday, Mr Joyce read out sections of the roadmap to the parliament and was heckled by the Opposition, questioning if it was the first time he had read the plan.

Livestock feed supplements, fuelled by Australian seaweed, were flagged in the document as an emerging technology that could dramatically reduce methane emissions, increase on-farm productivity and create a new $1.5-billion agricultural seaweed sector within two decades.

The 2050 plan highlighted more than $300 million had been poured into developing the technology over the past six years.

Alternative forage feeds, and genetic selection and breeding for low methane traits were also mentioned in the plan as ways to reduce agricultural livestock emissions.

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Finance Minister Simon Birmingham said the government would look to reduce methane emissions by 80 per cent with new technologies at a future point in time.

"There has been some talk about some nations making short-term pledges in relation to methane, Australia is not pursuing that," Senator Birmingham said.

"It would particularly impact on the agricultural sector and we don't want to impose a short-term burden."

Mr Joyce suggested the only way to reach a 30 per cent methane reduction target would be for farmers to shoot their own cattle, a claim Emissions Reduction Minister Angus Taylor repeated.

"We won't sign our country up to policies that undermine the prosperity of our regions or make life harder for everyday Australians and that no affordable, practical and large-scale way exists to reduce it other than by culling herd sizes," Mr Taylor said.

However, the industry has criticised the idea of livestock culling to achieve net-zero as a strawman argument.

Founder of Queensland-based agritech company DIT AgTech, Mark Peart, said the claim simply wasn't true.

"The additives to reduce methane are proven tested and ready to deploy to reduce methane in livestock," Mr Peart said.

"The issue has always been how to deliver these additives at scale.

"DIT AgTech is building a technology platform that can deliver these additives at scale to hundreds of millions of livestock via water to meet the 2050 targets."

The Meat & Livestock Australia has committed to a red-meat sector goal of becoming net-zero by 2030, while the National Farmers' Federation has backed an economy-wide goal of 2050.

Founder of Queensland-based agritech company DIT AgTech, Mark Peart, said the claim simply wasn't true.

"The additives to reduce methane are proven tested and ready to deploy to reduce methane in livestock," Mr Peart said.

"The issue has always been how to deliver these additives at scale.

"DIT AgTech is building a technology platform that can deliver these additives at scale to 100s of millions of livestock via water to meet the 2050 targets."

Mr Joyce will be Acting Prime Minister from Thursday evening, when Prime Minister Scott Morrison flies to Glasgow, to present Australia's new net-zero plan to the United Nations Climate Change Conference.