Taranaki's first case of Mycoplasma bovis has been confirmed.
The Ministry for Primary Industries said the herd on a Taranaki property had tested positive for the disease.
A Restricted Place notice has been placed on the farm.
MPI Mycoplasma bovis director Geoff Gwyn said the M. bovis response team had worked hard to establish whether the property was at risk of being infected and had established the risk was high.
Gwyn said it was a sensitive situation and extremely trying for the farmers involved.
"For privacy reasons we cannot go into specifics of the property involved, however I can tell you that a number of animals will be culled."
He said MPI was working with the farmers. "While every decision is made with the aim of eradicating the disease from New Zealand, we are well aware that the effect of this eradication response has on individual farmers. We are wrapping as much welfare support around the owners of the property as possible and are working with them and their support networks to ensure they are well supported through this process."