The Green Party wants Agriculture Minister Damien O'Connor to phase out an imported animal feed to help to help address the climate crisis.
Palm kernel expeller is a by-product of the palm oil industry, and is mainly used by the dairy industry.
The product has been linked to the destruction of rain forests and loss of biodiversity in South East Asia.
Agriculture Spokesperson Teanau Tuiono has published an open letter saying the feed increases the industry's climate emissions, making it harder to reach the country's reduction targets.
He says it allows for higher numbers of cows than locally grown feed sources can provide for.
It is a far cry from the grass-fed, sustainable products people here and overseas expect from New Zealand farmers, he said.