How to indentify mycoplasma in dairy cows

A hot topic among many farmers and vets is the issue of Mycoplasma. With New Zealand enforcing an aggressive culling policy on cows affected by it, it raises the question; do we know enough about it? Are we being proactive? So it goes without saying that prevention is better than a cure, especially when discussing calf health and performance.

Mycoplasma are a group of small bacteria, in the UK the most prevalent strain is Mycoplasma Bovis (M.Bovis). Mycoplasma is of great concern among the UK farming industry because it is very difficult to treat. It is a bacteria with a number of its own defence mechanisms. It has no cell wall, so the most-commonly-used antibiotics, such as Penicillin’s and Cephalosporins, are not effective. It can change surface proteins which helps it to evade a calf’s immune system and go undetected. It can also produce a biofilm which temporarily “hides” from the immune system and antibiotics.

In calves and youngstock infection of M.Bovis can result in a range of symptoms, depending on the area of the body affected, but most frequently causes;

• Pneumonia
• Conjunctivitis
• Inner-ear infection
• Arthritis
• High temperature
• Runny nose
• Head tilt
• Abscess
• Crusty eyes

In extreme cases discharge comes from the ear canal and there can be swelling over the eyes and forehead and a reduction in appetite.

Identifying an infection with M.Bovis can be difficult, but there are two main ways in which it can be found. Firstly, by classical diagnosis, which is via a selective culture medium with prolonged incubation in an enriched carbon dioxide environment. This can take up to 21 days, which in the event of an outbreak can be costly, however this method allows individual species to be identified, giving a more targeted treatment protocol. The second method is by PCR. A culture-based broad scan will give a positive or negative result, it’s very quick but it won’t identify the species. It is important to note that timing of the sample taken is crucial and your vet should be contacted if you have any concerns.

Bulk tank culture and PCR have been advocated as ways of monitoring and screening herds for the presence of Mycoplasma Bovis mastitis. However, successful bulk tank culture is reliant on a clean milking routine to minimise contamination with environmental organisms.

Transmission of M.Bovis is usually by close and repeated contact, infected milk can also be a source, including colostrum. Animals that are already immune suppressed are more likely to contract the disease, most commonly calves that are BVD positive. M.Bovis can also be spread via feeding equipment such as teats, feeders, tubes and also from dam to calf post calving.

• One of the highest risk factors affecting a farm is from bought in cows with an unknown disease status, therefore a closed herd is recommended, or any bought-in-cows should be quarantined and tested before integration into the herd.
• It is also vital that unpasteurised milk is never fed to calves and colostrum should ideally be pasteurised too using a Store N Thaw machine.
• Because of the risk of dam-to-calf transmission, it is suggested that the calf should be removed to a clean and hygienic area as soon as possible after birth.
• Try to operate an all-in, all-out system to minimise young animals coming into contact with older animals.
• Ensure adequate ventilation in youngstock buildings and keep the stock clean and regularly mucked out.
• Disinfect all calf feeding and rearing equipment after each use to avoid pen to pen transfer
• Isolate sick animals
• Treat quickly
• Ensure an adequate vaccination programme.
• Take time to discuss with your vet if you feel your calves are at risk of a M.Bovis infection, early detection within a herd can save the headache of an outbreak within the youngstock.