By Sarah Hampson

Mycoplasma Bovis infection is a common challenge we face on farm and can cause a significant impact on the health and performance of your calves. Whilst it is found globally, in the UK M. Bovis is most commonly seen as calf respiratory disease and outbreaks of mycoplasma mastitis are very rare.

What are the signs and when to suspect it in calves?

• Pneumonia from as young as four weeks old up to five months
• Eye infections
• Ear infections are seen as ear drooping and head tilt
• Swollen joints

Unfortunately, Mycoplasma is a typical ‘iceberg’ disease. This means that for every one calf you see with pneumonia, there will be three more with lung damage which go under the radar.

The knock-on effect of these problems is poor growth and long-term performance, increased antibiotic usage and increased mortality.

If you see one or more of the above signs or are experiencing a poor response to treatment, it may be that Mycoplasma bovis is involved.

Sadly, most diseases are bought and paid for. As M. Bovis is endemic and highly prevalent in the UK, the highest risk for introducing it to your herd is through buying in infected cattle. Calf rearing units, buying from multiple sources, are therefore very high-risk systems to suffer with this disease.

Whilst closed herd status is the safest way to avoid introduction of M. Bovis. There are screening tests available which can be used to check if a purchased animal is infected before introducing it to the herd, however no test is 100%. If your herd is naïve and you buy in infrequently (e.g. stock bull) then testing would be highly recommended. If you are a flying herd, asking herd disease history and buying from low somatic cell count herds will reduce but not eliminate, your risk.

Mycoplasma can spread from cows to calves through contact in the calving yard or through feeding infected milk. Feeding calves whole milk is a big risk factor if mycoplasma is present in the adult herd so this is something to consider if you are looking at this strategy.

Particularly high-risk milk is that from high cell count or mastitis cows, so always avoid feeding that to your calves. Although colostrum is not thought to be a major route of transmission, pooling it could potentially result in outbreaks.

Pasteurising milk is an effective way to control mycoplasma, however even with this step only saleable milk or fresh cow milk should be fed to calves.

Once in the calves, Mycoplasma spreads like any other respiratory bug through nose-to-nose contact or in the air. Therefore, general pneumonia control strategies which improve air quality are key reducing transmission in youngstock. This should include good ventilation, small group size and adequate space per calf, good drainage and grouping calves of similar ages.
Vaccination can also play a key role in reducing spread, which can be given from as early as one week of age.

Treatment

Prevention is always better than cure however if you have calves with clinical signs, it is essential to use the right antibiotic, treat as early as possible and give an anti-inflammatory alongside. Fluids may also be of benefit and providing a warm dry environment for recovery should not be overlooked.

It is important to understand that the antibiotics used to treat mycoplasma do not kill the bacteria they just stop it growing for a short period of time, giving the calves immune system time to clear the infection.

Therefore, calves which have experienced good colostrum transfer and are on a good plane of nutrition, will have more ability to fight the disease so you will see better response to treatment.

It’s helpful to understand what bugs are causing disease on your farm as this can guide prevention strategies and treatment choices. Testing can be done via bulk milk, blood samples, or nasal swabs. We currently have support for free testin,g so if you think Mycoplasma could be affecting your stock, please speak to your vet.

Ultrasound scanning of calves’ lungs is a newer technique we can also use to help manage and monitor calf respiratory disease. It allows us to look for look for lung damage which may otherwise go undetected. The aim is for better monitoring, earlier and more successful treatment, and lower overall antibiotic use.

• Purchase decisions – the biggest risk for bringing it into the herd is in a carrier cow. If you need to buy in, ask the herd history, buy from low somatic cell count herds, and consider testing.
• Avoid housing sick or mastitis cows in the calving yard
• Move newborn calves to clean calf housing promptly.
• Do not feed calves mastitis or high cell count milk
• If feeding whole milk, consider pasteurisation
• Reducing the spread between calves should focus on optimising air quality.
• Vaccination can help in control
• Early detection and correct treatment with the right antibiotic will improve recovery
• Immune-compromised calves will get more disease and respond more poorly to treatment. Ensure good colostrum transfer and nutrition.