Managing Mycoplasma bovis (DairyNZ)

In July 2017 the bacterial infection Mycoplasma bovis was found in cattle Oamaru. At last count there have been 24 farms found with the bacteria.

While MPI is working to control the spread of the disease in New Zealand and decide if it is possible to eradicate it, DairyNZ is helping farmers protect themselves and their animals.

 Mycoplasma bovis is a bacterium that causes illness in cattle, including udder infection (mastitis), abortion, pneumonia, and arthritis. Internationally the bacterium is widespread. Its detection in South Canterbury was the first time it had been found in New Zealand.

 Mycoplasma (a bacteria) lacks a cell wall and because of this, they are unaffected by many common antibiotics. There are over 125 species in animals. More than 12 occur in cattle but few result in disease. M.bovis is the most severe. It is very hard to detect and for cows to fight. It does not cause disease in humans.

The disease seems to behave differently in some countries with different production systems playing a role. MPI says the way the disease has behaved in New Zealand so far includes; mastitis in dry and milking cows, arthritis and late term abortions. Symptoms likely to be seen later in the season will include diseases in calves, including pneumonia.

Transmission

Shedding from infected animals - mainly from the eyes, nose, vagina, or rectum and via semen and milk, transmits the disease from animal to animal. Animals don’t have to be visibly sick to transmit the disease. Transmission between cows is likely to happen at milking time – and spread between farms by movement of infected animals or in-contact equipment (such as milking gear or AI equipment). Neighbouring farms can be infected by contact over a boundary fence, and untreated milk can also be a source of infection for calves.

Treatment

Treatment takes a very long time and doesn’t always work. Cows that recover from mastitis often continue to shed the disease and are treated as persistently infected. To produce a disease free property would likely require culling.

Diagnosis / Testing

MPI announced in January 2018 that it would extend M.bovis milk testing from Canterbury, Otago and Southland to include the rest of the country. In its press release it said that while there was no indication that the disease is present outside areas already identified, checking for other possible regional clusters was a prudent step.

The test involves taking 3 milk samples from every dairy farm. One is taken from the bulk milk as part of the regular testing and another 2 samples taken from discard milk. The extended programme is beginning in February and rolled out region by region. There is no reliable herd test.

MPI has looked at a range of pathways to try and determine how M. bovis arrived in New Zealand, including the possibility of live animal imports and cattle semen, and even milking equipment imports. DairyNZ’s Chris Morley says currently there is no ‘smoking gun’ - just a whole bunch of ‘maybes’.

DairyNZ has been working with MPI and their farmer stakeholders to inform and support farmers as the disease has been identified.

It is suggested that one of the challenges and the biggest risk for New Zealand is animal movement - a common part of the farming system. Animals leave farms for grazing. Calves get sent away. The challenge is that if infected animals co-mingle with animals from other farms, the disease can spread.

DairyNZ is reinforcing the importance of the NAIT animal records. It has been suggested that some farmers haven’t been keeping good accurate records in the NAIT system, which has made tracking the movement of infected cattle extremely hard.

Failings in the NAIT system have a lot of farmers in other parts of the country very concerned. Federated Farmers President Katie Milne says there are issues with entering records in NAIT - she says some farmers don’t have good computer skills and as a result records aren’t entered. She also says private sales aren’t always well recorded. Some farmers are also saying data flow between the various farm management data systems doesn’t work well.

Biosecurity Checklist

Helen Thoday is a team leader in the animal welfare team at DairyNZ. She says there is a lot of information to absorb, so DairyNZ has created the Biosecurity WOF, accessible through the DairyNZ website, to help farmers.

https://www.dairynz.co.nz/publications/farm/biosecurity-wof/

 Among the steps suggested to farmers to minimize the risks are:

Stock Movements:

-       stock movements carefully managed.

-       Get a pre-purchase check list before buying or leasing cattle – animal health status etc

-       Nait requirements – all movements - make sure animals have tags.

-       Talk to truck driver

-       Talk to grazier about biosecurity

-       Keep new arrivals separate from herd for 7 days.

On Farm steps:

-       Signage at the gate - plus contact numbers – restricting access

-       Water bucket and scrubbing – spray bottle

-       PPE gear on-site - including some for visitors

-       Cleaning farm equipment – esp contractors

-       Farm layout - restricted entry point

-       Green / Blue and Red zones

-       Sick animal paddock

-       Boundary fences

-       Have a farm Biosecurity plan

All infected farms have been placed under Restricted Place Notices (RPNs), legally preventing the movement of animals, equipment, and risk materials from these properties.

MPI can also issue a Notice of Direction (NoD) to farms when an inspector or authorised person believes that movement of stock and other risk goods from a property poses a risk of spreading Mycoplasma bovis. For example, MPI may issue a NoD when animals from infected properties move to that property, but no testing has happened yet.

Bryson Hargreaves is part of a farmer action group in his area set up in response to M.bovis. He has been living with the disease in his area for six months. He says it is a farmer problem and farmers have to solve it. “There’s no point getting upset with MPI. It is what it is and it’s here.”

Those in his area who have the disease are extremely stressed. “And they’ve done nothing to deserve this – it has just arrived.”

Bryson reckons there are a number of things farmers can do themselves to minimise risk. He says there’s a job to do getting boundary security right, minimising access points – all the key things that DairyNZ is advocating. He talks particularly about the need to be right on top over animal movements, “ask the questions that as farmers we don’t normally like to ask.”

He doesn’t think there will be any particular changes to farm systems - just farmers needing to think a lot more seriously about what they do. “If you are going to buy stock in – you review who you are going to buy them from and know where they’ve come from.”

On NAIT, Bryson says the system was there to protect farmers and many have let themselves down by not using it properly, but he is not prepared to criticise the system. “We could point fingers and blame everyone but that’s not going to fix M.bovis.”

He says it is up to farmers to step up and do everything they can to minimise the spread. In the longer term, he believes NZ farmers can learn to live with M.bovis just as we have learned to live with and control bovineTB. “We have protocols in place which will work in this situation.”

Align Farms Longland is 275ha effective. It is fully irrigated – under pivots and long lines. It was a dairy conversion 5 seasons ago. Manager Matt Bell says the farm is well laid out. They milk 1100 cows at peak in a 70 bail rotary.

He says that when M.bovis reared its head, he and the others in the Align Group sat down and planned their biosecurity using the DairyNZ WOF template. They went through the risk and have elected to stop bringing cows in. They’ll be a closed herd after this season. All boundaries are secured and there are plans afoot to strengthen the eastern boundary. He says one boundary butts on to another farm. They stay in contact with that farmer and if cows are in the neighbouring paddock they don’t put their own cows near it.

Risks identified include transport. They have sent a letter of intent to all their suppliers with an outline of our expectations regarding biosecurity - including any truck that has been on anther farm paddock to turn up clean. The farm has red and green zones. All contractors have a map. Red zone is where cattle are. So when you enter the cow shed you are entering a red zone. The intent is to use Align Longfield’s own farm vehicles to move visitors around.

There are footbaths at the shed and a spray pack. There are signs at the gate with a restricted entry notice and contact details for Matt and his workers.

Matt also says they are looking at what their options are with bulls for next season. On option is to write to their suppliers and get some kind of reassurance that their bulls are M.bovis free. Another option is not to use bulls at all. “We’re worried about it. It’s not Foot and Mouth but it is still a concern. It is in Mid-Canterbury. It has certainly sharpened up our practises.” The farm has had bulk milk tests. All the red cows – or cows outside the milking herd have also been tested. “We haven’t heard anything – so we presume the news is good.”