NZ readies for fight against deadly cattle disease

Destructive and contagious cattle disease Mycoplasma bovis has finally reached New Zealand's shores. Is it simply bad luck, or one of the costs of farming intensification?

Bacterial disease Mycoplasma bovis has no known cure, and can cause mastitis, abortions, pneumonia in cows and calves, and is potentially fatal.

Initially found on two Van Leeuwen Dairy Group properties in South Canterbury about five weeks ago, early detection fuelled optimism it had been contained.

After cropping up at a third farm in the area - the location of which was kept secret - the disease has now spread as far north as Rangiora, bringing the total number of infected farms to six. 

The Ministry for Primary Industries has been both criticised and praised for its response. Either way, it has released a strategy on its website, which reassures farmers it is doing everything in its power to contain the disease, including legal notices to prevent any movement of animals, equipment or materials from the identified properties.

No one yet knows how Mycoplasma bovis entered New Zealand, but MPI is working on that too. The Ministry is also toiling alongside the country's “animal production industry bodies and veterinarians” to stave off the spread.

As New Zealand works to contain the disease, some are asking whether Mycoplasma bovis is a symptom of the quest to increase productivity.

And is that quest - which comes at the expense of issues like imported diseases and more antibiotics in our food - reconcilable with the environment as long as we adhere to other concerns like nitrogen limits?

An ambivalent isolation

New Zealand both suffers and benefits from its isolation. From a biosecurity perspective, our perch at the bottom of the South Pacific is an advantageous one.

However, our biosecurity protection systems aren’t without flaws.

Like the emergence of Mycoplasma bovis, our armour was shattered with the arrival of the varroa mite in 2000.

Agricultural economist Peter Fraser says we were one of the last “major” countries in the world to get it. And it hit us hard.

“Once it was out of the bottle, it was everywhere. Now we have to just live with it.”

Fraser says the questions we have to ask ourselves, now, are: is this a case of us merely catching up with the rest of the world? Or are we catching up with the world because of our shift toward intensified farming practices?

“I’m not saying we’re going into industrial feed lots, but compared to what we have had … it’s a country mile from a Taranaki family farm 30 years ago with 150 cows.”

Veterinarian, farmer and ecologist Dr Alison Dewes says New Zealand’s move towards more intensive systems - with more animals in close confinement - plays a significant role in disease transmission between animals.

The way Mycoplasma bovis is spread requires proximity between animals, so the way they are being housed is conducive to a wider and faster spread of the disease.

We are now even breeding the cows themselves to suit those higher-density systems, she says.

“Your normal, free-range cow in New Zealand isn’t bred for these systems so that’s why we’re importing semen from North American cows.”

Northern Hemisphere genetics are what’s behind the high input/high output cattle suited to high density farming.

The “outdoor” cows typical of New Zealand, on the other hand, are far more resilient, but their pasture-led lifestyles don’t align with high production, she says.

“You need the right animal for the right kind of farming model.”

Intensive systems also tend to require more health measures and interventions to stop - and even prevent - stock diseases. This is already being felt in the overuse of antibiotics on animals, compromising their efficacy for humans.

“Over half of the antibiotics that come into New Zealand … are used for agriculture and what we’ve got to be doing is reserving those antibiotics for human health.”

Traditionally, New Zealand farming systems haven’t needed high levels of health interventions, but as we shift towards high-confinement models, we’re seeing situations where farms need vast numbers of preventative antibiotics to even function, says Dewes.

“That’s actually going in the opposite direction to where we need to go for sustainability and human health ... Everything is riskier because you need quick fixes.”

One only has to look across the Tasman to see how a similar pattern unfolded in Australia, where farming methods have been intensifying for longer and on a much larger scale.

When Mycoplasma bovis took hold there, the spread was swift and devastating, she says.

So why are we moving towards high-density systems if they are so much more vulnerable to disease and biosecurity incursions?

The nitrogen problem

Because farmers are trying to adhere to nitrogen leaching limits, there are really only two extreme pathways they can take, Dewes says.

“You can [either] put all your cows in a barn and collect the effluent and cut and carry the feed … or the other way you can go to reduce your nitrogen is to tread a whole lot lighter.”

The limits put farmers into a difficult situation, where they are adapting to sustainability standards, only to open their operations up to disease and vulnerability.

"Farming in the last five years has had to adapt to managing its spillover onto the environment.”

Dr Alison Dewes

Dewes goes as far as to describe farmers as the “victims” in this. Whether or not you see it that way, the pressure they face from regional councils and the public is indisputable.

“We’ve got this pressure on farmers right across the country to reduce spillover into the environment so it’s forcing the conventional farm systems of the past 30 years to make changes.

“In a way, farming in the last five years has had to adapt - in a very short space of time - to managing its spillover onto the environment.”

Farmers have been hit somewhat “broadside” as their leadership fights for ‘business as usual’ all while public patience on agriculture’s licence to operate becomes exhausted, Dewes says.

“You have to question, has there been a failure in leadership? You could argue that regional councils and Dairy NZ knew there were nitrogen limits coming 15 years ago …”

However, Dean of Veterinary Sciences at Massey University Dr Jenny Weston says the intensification of farming in New Zealand hasn’t got to a point where it could be considered a player in the spread of Mycoplasma bovis.

The spread of the disease requires reasonably close contact between cows, and New Zealand has benefitted from not having much in the way of feedlots, she says.

“If we moved to a system where we had lots and lots of cows housed for long periods of time then that would aid the spread of this particular disease.”

However, the country’s current levels of agricultural intensification aren’t high enough to justify that theory, she says.

Mycoplasma bovis has been reported as being “highly contagious”, which is misleading, Weston says. The disease is contagious, but nowhere near to the same degree as something like foot and mouth disease, which - airborne - can travel between properties.

Being equipped to respond to something like this is never easy, and overall, MPI has reacted in the most effective way it could have, Weston says.

“We’re nothing like a lot of other countries.”

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