Whanganui is reasonably remote from the areas where cattle are being culled to prevent the spread of a new bacterial disease.

But having your entire herd slaughtered to prevent the spread of Mycoplasma bovis would be "huge", Federated Farmers Wanganui dairy chairman Brian Doughty said.

"I wouldn't want to be in their shoes."

Rural support trusts have been asked to work with the affected farmers.

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There may be no known infected properties here, but there are farms with cattle that have been moved from infected or possibly infected properties. But local farmers are not panicking, Doughty said.

The bacterial disease probably got to New Zealand in 2015. How it got here is unknown.

It was first found on a farm near Oamaru in July last year. The first infected properties were all in the South Island.

Then there was an infected property in Hawke's Bay, then another in south Hawke's Bay on May 3, and one in Waikato on May 14. It brought the number of infected properties to 39.

An estimated 22,000 cattle from infected dairy and beef herds are to be slaughtered, and their owners compensated for the loss. By May 10, 11,000 of those had been killed.

It had to be done, Doughty said, to preserve the possibility of eradicating the disease from New Zealand. But he thinks farmers here will probably have to learn to live with it.

"It's being managed overseas in lots of other countries and we need to do the same."

A United States website says proper stocking density, environment cleanliness, minimising stress and preventing infected calves from infecting healthy animals are all good management tactics.

Doughty is counselling farmers to keep on farming, rather than shut down. But they will need to be more careful about where they source new stock.

It would help if the National Animal Identification and Tracing (NAIT) system had been designed better, he said, and if it had been better followed by stock owners.

Calf rearers and people who trade in cattle will have to make especially careful checks before buying.

It doesn't help that the disease is so hard to detect. Tests can show false negatives as well as false positives and stakeholders are working toward producing a definitive test.

The Ministry for Primary Industries is to decide whether New Zealand should eradicate or live with the disease at the end of May.

MYCOPLASMA BOVIS
+ a bacterial disease of cattle
+ not treatable by antibiotics
+ spread by milk, semen and nasal fluid
+ can be dormant, with no signs
+ hard to detect for sure
+ no human food safety risk with milk or meat

SIGNS IN COWS
+ lameness
+ mastitis
+ abortions

SIGNS IN CALVES
+ coughing
+ ear discharge
+ infected eyes