The country is trying to eradicate Mycoplasma bovis, a disease that causes mastitis, pneumonia, and arthritis in cows. Authorities insist the decision is to stop future production losses and is unrelated to food safety.
New Zealand's Prime Minister Jacinda Ardern on Monday ordered the culling of more than 150,000 cattle, having made what she described as a "tough call" to try to eradicate a strain of Mycoplasma bovis.
The disease, which causes udder infections, pneumonia and arthritis in cows but has no effect on milk and meat for human consumption, was first discovered on a farm on the South Island last July.
"No one ever wants to see mass culls. But the alternative is the spread of the disease across our national herd," Ardern said, adding that it was vital to protect farming, a key sector of New Zealand's economy.
Two years to complete
She said the cull, the majority of which would take place over the next two years, would aim to eradicate the disease completely.
A program to slaughter some 26,000 cattle is already underway. A further 126,000 animals, at 192 properties, will be added to the cull, at a cost of NZ$886 million (€526 million, $615 million).
The government said it would bear around two-thirds of the cost, while farmers and the cattle industry will pay the rest.
The slaughter represents only a fraction of New Zealand stock, a herd of 10 million cattle in more than 20,000 dairy and beef farms. That's more than two cows per person in the country.
Although all farming lobby groups have supported the decision, many farmers are reported to be angry about the cost and loss of their herds.
Katie Milne, the national president of the advocacy group Federated Farmers, insisted that authorities would try to make sure affected farmers had all the support they needed, including adequate compensation.
While other countries have sturggled to eradicate the disease-causing bacteria, New Zealand thinks its isolated location could help
Agriculture Minister Damien O'Connor admitted that most of the cows to be culled are healthy.
"This is a necessary, unfortunate part of not having yet a test that clearly identifies the individual animals," he said.
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Origin still unknown
An investigation into how Mycoplasma bovis got into the country is still underway. Since it was first detected, the disease has spread to 37 farms, and computer modeling suggests it will eventually reach some 142 farms.
Authorities are still trying to determine if the strain arrived through imported live cattle, frozen semen, embryos, veterinary medicines and biological products, feed, used farm equipment, or other imported live animals.
No country has managed to eradicate Mycoplasma bovis so far. Until July New Zealand was one of only two major OECD dairying countries that were free of the disease. Norway is now the only one.
Officials say they should know by the end of the year whether the eradication plan is working.
mm/msh (AFP, AP, dpa)