Liam Bawden BVSc
There have been plenty of questions from farmers regarding M. bovis recently and slowly we are getting more answers, however where there are gaps in our understanding of the disease and how far it has spread, we have to act with caution.
Genetic testing has shown that it is likely M. bovis came into New Zealand in 2015 and whilst undetected, spread with cow movements over the next 2 years. Some cows went to a Van Leewen farm in this period, where in 2017, M. Bovis was recognised by a local vet.
Currently there are 43/20,000 farms (as at July 26th) that have had active infection. Only 5 are in the North Island. So far all infected farms have been traced back to the original farms via NAIT, which is one of the reasons eradication was given the go ahead. When bulk milk testing begins again this spring, we will see if there are any surprises.
What is it??
Mycoplasma bovis is a very small bacteria without a cell wall. Most antibiotics work by destroying cell walls which makes mycoplasma difficult to kill. Disinfectants however, work very well.For mycoplasma to survive in the environment it needs to form a barrier called a “biofilm”. This is made up largely of cholesterol. Milk is high in cholesterol and this is why mycoplasma survives so well in milk or milk residue.
M. bovis can sit on the tonsils of a healthy cow or it can move to invade the lungs, inner ear, joints, and udder where it may or may not cause disease. This makes it hard to find in an individual animal and is why we are testing on a herd basis to look for exposure (rise in antibodies to M. bovis in blood or milk). These antibody levels may take months to increase which is why biosecurity and repeat testing is so important and why we will have some idea if eradication is working over the next two years.
There is no food safety or human health risk. M. bovis has only adapted to cattle as a host.
What’s the plan??
Vat milk samples will be tested regularly as well as all mastitis samples and blood testing surveillance of beef farms is likely to commence this coming summer.
What can you do?
Take biosecurity on your farm seriously, especially while we are trying to eradicate. The highest risk of introduction is repeated contact with an infected animal or bringing an infected animal onto your property. The highest risk of rapid spread is feeding milk infected with mycoplasma to calves.So, if you must bring in cattle (not recommended) make sure they are NAIT tagged, the movement is recorded. If you can, buy animals from a closed herd. It is also good practice to quarantine new animals for 7 days.
Many farmers will be bringing in bulls for mating. Try to buy from closed beef breeding herds that have no dairy or dairy cross animals on their farm. These bulls should also be BVD tested and vaccinated as usual.
Please avoid selling milk to calf rearers, as this will risk rapid transfer to multiple animals. Use milk powder instead.
If you have any strange cases of disease, do not hesitate to call us. The following are diseases commonly seen with M. bovis. Mastitis in dry and milking cows (not responding to treatment as expected) Arthritis in cows Late term abortions Premature calves Pneumonia in calves Conjunctivitis in calves
If you are unlucky enough to have M. bovis, you want it found while there is compensation available.
Individual animal testing in healthy animals is not recommended as it is not a sensitive test however it may be carried out in specific circumstances. If you have any questions please call us, we are happy to help however we can.