New Zealand's first outbreak of a serious bacterial cattle disease was well under control, the Primary Industries ministry said on Friday, with stock movement restrictions in place and testing continuing.

News of the discovery of mycoplasma bovis earlier this week on a single farm in the world's largest dairy exporter briefly knocked the local currency lower, given the importance of the industry to New Zealand's economy.

The ministry said movement restrictions had been placed on 16 individual properties after the infection was confirmed at one farm in the Van Leeuwen Dairy Group, a large scale dairy business on the country's South Island with some 12,550 cows.

"At this time we are still determining the scale of this situation through on-farm sampling and testing, and tracing of movements of stock on and off the properties," the ministry's regional controller Dr. Chris Rodwell said in a statement.

The ministry said a farmer had euthanized a small number of animals voluntarily for animal welfare reasons.

The disease, which is common in many countries, can have a serious effect on cattle, but does not infect humans or present food safety risks to milk or milk products, the ministry said.

The infection is spread by close contact between animals and not across big distances by wind or water. It can also be present in milk and be transmitted to other cows in that way, it added.

The New Zealand dollar was slightly lower on the day, having touched its highest in over two years in the previous trading session.

Analysts said there had been concerns of a knee-jerk reaction to news of the disease that could affect market access for New Zealand's dairy products.

"But that doesn't seem to have happened with the passing of time already, so at this point we are thinking it is going to be a relatively small issue," said Doug Steel, senior economist at BNZ.