Federated Farmers is making a last-ditch stand aimed at scuppering the much-debated national animal identification and tracing system, NAIT.
It's urging Parliament to ditch the legislation that will provide the legal framework for the compulsory scheme, which is due to be phased in from late this year, starting with cattle and then deer.
There's no plan at this stage to include sheep or other farm stock.
Livestock will have to wear radio frequency tags, the aim being to limit the trade fallout of a disease outbreak and strengthen the biosecurity system by making it easier to track the movement of stock.
But Federated Farmers' dairy chair, Lachlan McKenzie, has told Parliament's primary production select committee - which is considering the NAIT bill - that the scheme should not be compulsory.
He says the biosecurity argument is flawed because the scheme will not keep track of all livestock, nor feral animals.
The Animal Health Board, which is responsible for bovine Tb control, shares some of Federated Farmers' concerns about not knowing what will be in the regulations governing the scheme because MAF is still drafting them.
The board's Nick Hancox told the select committee, however, that it does see real benefits in the scheme.