Mr Peters says he isn't convinced with the Government's Mycoplasma bovis plan.
"Standing back and allowing the disease to spread would simply create more anxiety for all farmers", she said.
The decision was taken to "protect the base of our economy - the farming sector", Ardern said.
Mycoplasma bovis was first detected in New Zealand in July previous year, and manifests in mastitis in cows, severe pneumonia, ear infections and other symptoms. Found in Europe and the US, the bacteria can cause cows to develop mastitis, pneumonia, arthritis and other diseases. Even if cows appear to be healthy, officials will "kill all cows on any farms where the bacteria are found". Some of the slaughtered cattle may be used for beef, but others will be buried on farms or in landfill. According to AP, officials indicated they won't be able to tell until the end of the year whether the mass cow killing plan will work.
Accordingly, about 150,000 cows, bulls, and calves will be killed in a desperate measure to keep under control and ultimately eradicate the spread of Mycoplasma Bovis in the country. She said they would try to make sure affected farmers had all the support they needed, including adequate compensation.
"This is a tough time, and the pain and anguish [affected farmers] are going to go through is really ugly", she said.More news: China raises ‘combat readiness’ as USA warships enter disputed waters
"And we have to support them as neighbours, community members, farmers, friends".
But the Government hopes the early discovery in New Zealand gives them a chance of eradicating it here. That's more than two cows per person in the country.
New Zealand's dairy sector contributes about NZ$7.8 billion annually to the country's gross domestic product and accounts for around a fifth of the country's exports.
New Zealand police have launched a combined investigation with the Ministry of Primary Industries into how the disease made its way to New Zealand, and leapt between the two islands.
Since the identification of the disease, near about twenty-six cows have already been slaughtered.