These are words to strike fear into the heart of many farmers. However, as lifestyle farmers there are far fewer risks for you and your cattle than there are for many commercial dairy farmers. Big commercial farms are certainly being hit hardest. So what does this outbreak mean to us as lifestyle farmers?
We hope this article will help clarify the situation.
If you haven't bought adult cattle, calves, or raw milk onto your farm in the last 3 years, it is extremely unlikely that your cattle are infected. If you had bought cattle from a confirmed or suspected infected property it’s likely that by now you will have been contacted by MPI, who are tracing the movement of all cattle from known infected properties as part of an eradication programme.
Most of the cases so far have been on commercial dairy farms, but 19 beef properties, and 2 other properties have been confirmed as infected. At this stage it appears the disease has been spread from farm to farm by movement of infected cattle (i.e. cattle that carry the bacteria in their body), but overseas, feeding of raw milk to calves is a known risk for spread of Mycoplasma bovis. The disease is spread between animals within a farm by direct contact between cattle, or from cows to calves in milk. It isn’t spread by wind and there’s a much lower risk of spread by dirty stock trucks, clothes or equipment.
Surveillance to date suggests the disease is not widespread within the national cattle population, and appears to be limited to a network of farms connected by cattle movements. Given this position, and the potential impact the disease could have in New Zealand, the government decided to pursue phased eradication – announced in May 2018. In addition to the ongoing tracing work, a second round of bulk milk surveillance is planned for spring 2018 .
Other livestock species are considered to be low risk for spreading the disease. Mycoplasma bovis poses almost no health risk to other farm animals, or to humans, as it is host-adapted to cattle. The bacteria do not survive for long outside their cattle host, however any object such as AI gear or equipment contaminated with milk could theoretically transfer bacteria.
One of the largest challenges for eradication is that Mycoplasma bovis is difficult to detect in cattle that are infected with the bacterium but not showing signs of disease. Testing is being performed on blood and milk samples, and swabs taken from the tonsils. These are being carried out by MPI on all cattle thought to have been in contact with infected cattle. As well as this, extensive screening tests are being carried out on bulk milk samples from dairy farms across the country. Because it’s hard to identify cattle with Mycoplasma bovis, it follows that determining a herd is free is not easy.
MPI has strict movement controls in place to stop the disease spreading further than it already has. When the infection is detected, the only way to eliminate it from the herd is to cull all the cattle (because tests are not guaranteed to find all infected individual animals). This is of course hugely distressing to the farmers whose apparently healthy productive cows are sent for slaughter. They need our support.
It seems likely that more infected herds will be discovered as testing continues, but MPI hopes that the steps taken so far will make real progress towards eliminating the disease. A review of the eradication decision is expected in early 2019, after results of the spring 2018 bulk milk testing.
The disease was first recorded in this country in July last year, and at the time of writing (3rd July 2018) it has been recorded on 53 farms (of which 42 are still considered 'active') - in Waikato, Hawke’s Bay, Wairarapa, Manawatu, Canterbury, Otago and Southland. It seems that the disease has been present in New Zealand since late 2015 – but because many cattle do not show disease when infected, it wasn’t immediately diagnosed. 231 farms have movement controls in place, and a further 135 properties are under assessment. So far 29,000 cattle have been culled, it is unknown how many cattle may be culled over the course of eradication.
In most western countries, Mycoplasma bovis infections are well established. New Zealand cattle have only recently become infected and the disease is not widespread, and MPI considers that eradication is achievable. If we are successful, we would be the first country in the world to achieve eradication. While the effort will be expensive and laborious, MPI considers it would be well worth while.
What can you do?
If you suspect you have cattle that could have the disease contact your veterinarian.
Don’t bring any cattle onto your property unless you can be sure they have not come from an infected farm.
Don't buy milk from other farms – use milk powder for calves if possible.
If you have to use raw milk, buy it from the same farm as where your calves are sourced. Milk isn’t traced nor is its movement regulated in New Zealand. Given milk’s potential to spread Mycoplasma bovis, it necessary to be able to trace milk – calves are traced via NAIT and so if milk is purchased from the same farms, the calves become a proxy for the milk if tracing is required.
Raw milk is best treated to reduce the risk of disease – talk to your vet if you intend to purchase raw milk.
Ensure your cattle have NAIT tags and their records are up to date.
Keep stock separate from your neighbours – consider double fencing the boundary, and have stock proof fences.
Clinical signs of Mycoplasma bovis disease:
In adult cattle, the signs of clinical M bovis infection are arthritis and mastitis in dry and milking cows (which doesn’t respond to treatment), late term abortions, and premature calves. In calves, clinical signs include pneumonia, conjunctivitis, lameness and ear infections (droopy ears, head tilt).
There is a great deal more information about Mycoplasma bovis on MPI’s website: https://www.mpi.govt.nz/protection-and-response/mycoplasma-bovis/
We would like to thank the NZVA for their assistance in writing this article