Federated Farmers expects more rigorous checks to be made on palm kernel imports in future.
Greenpeace accuses the dairy industry of contributing to the destruction of tropical rainforests to make way for oil palm plantations.
And the Green Party has challenged an assertion by Fonterra that palm kernel imported by its RD1 subsidiary, is sustainably certified.
Palm kernel extract, PKE, is used to feed dairy cows.
Federated Farmers says the Ministry of Agriculture has already tightened biosecurity checks on palm oil imports, following concerns about insects and contaminants found in earlier shipments.