The New Zealand dairy industry is grappling to deal with its first recorded outbreak of a highly contagious cattle disease commonly found in the world.
The Ministry for Primary Industries (MPI) was informed earlier this month of the outbreak on Mycoplasma bovis in a South Canterbury herd.
About 150 cows on the property have been affected.
One NZ politician is calling for those cows to be immediately culled.
NZ Labour's primary industries spokesman Damien O'Connor said he knew who the owners of the farm were, and that they had a large indoor operation with a number of other separate farms.
When Fairfax Media contacted the most likely owners, they said they had no comment but the Ministry of Primary Industries (MPI) should be approached.
An MPI spokeswoman said the ministry would not reveal the names of the owners.
"Every animal on that property should be isolated and destroyed immediately, and while this seems drastic we must do everything possible to contain this and eliminate it from New Zealand," O'Connor said.
However, MPI said it was not a situation "that calls for immediate and widespread farmer concern".
Director of response Geoff Gwyn said there was currently no plan to cull any stock.
"We are urgently working to understand the spread of the disease and how widely distributed it may be," he said.
"It is not certain that this farm is the first case of the disease in New Zealand, which is why it is important to determine how widespread it possibly may be.
"Tracing animal and other movements on and off the farm is what is being done right now to help establish this.
"This is also the reason why we have put movement restrictions in place – this still allows for eradication if it turns out to be the most effective option."
The New Zealand Veterinary Association (NZVA) confirmed about 150 cows were affected on a property "which has around 1000 milking cows".
MPI was now tracing movements of animals on and off the property to ascertain if other properties are at risk.
An Australian expert Sydney University Associate professor John House agreed that destroying the cows would be the "cheapest" option to deal with the disease but warned it could have already spread through veterinarians or artificial breeding technicians moving from farm to farm.
"It's prudent to be careful," Assoc Prof House said.
"It's not like foot and mouth where it can spread for 1-2 kilometres on the wind, but once it's in a herd it's very contagious and difficult to eradicate."
Assoc Prof House said the likely way the disease arrived in New Zealand was through semen and embryo imports, and bringing in contaminated equipment.
New Zealand does not import live cattle, so the most "logical" means of arrival was semen and embryos. He doubted if it would come in via infected equipment.
"It would probably come in embyros and semen although it has been found infrequently. It survives freezing," Assoc Prof House said.
The disease had possibly been in Australia for some period before 2006 when it was first notified.
It was more prevalent in large herds of more than 1000 and was present in about 3.5 per cent of the national herd.
In adult cows the dominant manifestations were mastitis and arthritis, while in calves it was pneumonia and lameness.
Assoc Prof House said the most difficult period for a farm hit by the disease was the start, especially when people working with it had not seen it before.
Animal health and fertility manager for Dairy Australia Kathryn Davis said it was difficult to gauge the impact of the disease in Australia because there was no general monitoring done.
"There's been no government intervention, it's up to farmers to deal with it," she said.
There was an understandable fear of the unknown, she said, but farmers were not asked to cull their herds in order to contain the disease.
Mr O'Connor questioned why it took MPI so long to notify farmers in the region of the presence of Mycoplasma.
On Saturday tests had confirmed the disease, but many farmers he had spoken to knew nothing until Tuesday.
MPI said a "restricted place notice", restricting the movement of stock and equipment, was served "first thing" on Monday.
"This disease is slow moving and to implement wider movement controls across the region (or wider) is not appropriate based on the information we have," Mr Gwyn said.
"Disease management recommendations (including appropriate movement controls) are one of the first things to be discussed when an exotic disease is first identified and an urgent management meeting is held.
"This happened on Saturday afternoon once the disease was confirmed, and a meeting of experts was convened."
Mr Gwyn said it was too early to say how the disease arrived in New Zealand, "and the exact route of entry may never be known for sure. However MPI is reviewing all the possible entry means and attempting to trace back the pathway of the disease to its origin".
The NZVA said farmers should call their veterinarian if they suspected their dairy cattle were showing any of the clinical signs of the disease. These could include mastitis in dry and milking cows, arthritis in cows, late-term abortions and premature calves.
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