Beef sector must lift its game

He highlights the way they have brought in genes from all sorts of breeds and incorporated these into our base Romney flock.

This has included improving the fertility of the national flock and using terminal sires to improve the growth rate of our lambs, so they are more productive and carbon efficiency.

"Our lamb production is outstandingly good, but our beef industry is miles behind. We still have farmers in NZ who don't have yearling heifers. How can you have carbon efficiency if you don't mate a heifer until she is two years old? Some farmers might say it's difficult, but we have got to do it and we have got to produce animals that can do it," he says.

The big shift that's needed globally, says Smith, is to look at carbon emissions in relation to the nutrient value of a product.

He says when you measure cow's milk and oat milk this way, the cow's milk clearly comes out on top.

He says if NZ and other countries could tie their emissions to this criterion there would be significant progress globally on climate change.