Stuff - Police assisting M Bovis investigation by issuing warrants

Police have been issuing warrants to assist the Ministry of Primary Industries (MPI) with its investigation into how Mycoplasma bovis got into the country.

At an expert briefing at Parliament on Wednesday, MPI officials and Agriculture Minister Damien O'Connor explained what was being done to try and contain the spread of the disease, which is on a scale the country has "never faced before".

A Cabinet decision will be made on Monday on whether to continue with trying to eradicate M Bovis or shift to a management and containment plan.

"The police helped with issuing warrants to go and obtain information, the investigation is being undertaken by people within MPI, but the police will be called on when necessary," O'Connor said.

The biggest factor in the disease spreading is through cattle movement but that hasn't led to MPI putting a halt on farmers shifting stock during the change of season, known as gypsy day, on June 1.

O'Connor said a complete lock-down of stock was briefly considered but ultimately it would lead to animal welfare issues because cattle needed to be moved to get to where the feed is - if that didn't happen more stock would have to be culled.

MPI officials aren't expecting a significant spike in the number of farms with M Bovis after gypsy day.

"There are massive animal health issues here given the grass stops growing and people had planned to feed their cows in different places and if they're not allowed to move those cows, the cows will have to be slaughtered or feed brought to them.

"In some cases with the volume of feed - it's simply not possible to shift that," O'Connor said.

That meant there would be heightened checks on tracking where stock are going, that clean and sterilised trucks are used for transportation and possible infected farms and animals aren't being mixed with disease-free ones.

"In the end it's animal welfare. We have farmers crying out for decision and clarity because they don't have enough feed for their stock."

While gypsy day does "pose some risk, it doesn't cause the level of risk that would require us to make quite drastic decisions about preventing all animal movement," an MPI official said.

It's likely as tracking and tracing continues more disease-infected farms and herds will be identified, O'Connor said.

"We don't think gypsy day will cause a significant increase in that and if farmers all record these movements then we have the ability to track any animals that end up being infected," he said.

There's no clear cost for eradication or managing the disease but a figure coming out of Australia is that it costs $60 million annually to manage the spread and O'Connor said "that's probably in the ballpark".

Cost isn't a factor in whether the Government chooses to try and continue to eradicate M Bovis versus managing the spread because both options would end up costing about the same amount - the estimate is about $1 billion over ten years.

MPI officials said it's unlikely they'll be able to "definitively say" where the disease originated, but the genetics of the strain of M Bovis in New Zealand is being looked at, which is being mapped and will be able to be tied to a broad geographic area.

Currently Norway is the only country left in the world without the disease.

"Indications at this stage are that it's not the Australian strain, it's more likely the European one," O'Connor said.

The disease is predominantly spread through cattle movement but can also be spread through soil that can stick to machinery and that's why there's "strict hygiene protocols" for anybody going on or off locked down properties.

Imported semen, equipment and medicines are all being considered as part of MPI's investigation as to how the disease originally entered the country.

Picking up stock with the bacteria is difficult because most animals don't show any symptoms and testing only confirms an animal has M Bovis if the bacteria is "actively shedding" at the time.

"If we find one animal in a herd that is showing some immune response to the bacteria then we consider the entire herd to be affected because we have no test sensitive enough to pick it up on an individual animal level.

"So we know when an animal is positive, we don't know when it's negative," an MPI official said.

Countries are working on improving the testing but there isn't a better system at the moment, which means 23,000 animals are being culled on farms across the country and that number is likely to rise.