Farm groups have endorsed the decision to destroy 4000 cattle infected with the Mycoplasma bovis disease in the South Island.
On Thursday, the Ministry for Primary Industries announced it would cull livestock from five of seven identified properties near Oamaru.
The other two properties have already disposed of their infected stock.
"Since the start of this response in late July, we've carried out tens of thousands of tests of the infected, neighbouring and trace properties, as well as district-wide testing in Waimate and Waitaki, and a nationwide test of bulk milk," said MPI director of response Geoff Gwyn.
"This whole operation is about managing the disease, while keeping our future options open. We want to minimise the risk of further spread of the disease.
"Moving ahead with the depopulation of the affected farms will allow them to get back to normal business, as soon as it is safe to do so."
The decision has huge implications on the properties involved, but industry leaders say they accept it's the only option for New Zealand farming is to maintain its integrity on the local and international markets.
"We recognise the disease has come at a significant emotional cost to the affected farming families and their animals," says Federated Farmers NZ president Katie Milne.
"The process of culling whole herds will be very stressful for the people concerned, but the disease does not respond to treatment and cannot be vaccinated against.
"Culling is the only logical option to prevent ongoing suffering of the animals."
While Mycoplasma bovis is relatively common around the world, New Zealand remains relatively free of the disease and farming leaders want to keep it that way.
"Work is well underway on a Government-primary sector initiative to improve biosecurity," says DaryNZ chief executive Dr Tim Mackle.
"I urge farmers to have their say on this, when they receive information packs in the mail."