The government regularly tests cattle for tuberculosis using the tuberculin skin test. Animals which react to the test are compulsorily slaughtered, and restrictions are placed so that animals may not be moved on or off the affected farm (except direct to slaughter under license) until further tests show that the herd is clear. This process seriously disrupts farm business and can be very expensive. That is why it is important to try and prevent the disease from spreading.
As the disease is zoonotic (can spread to humans), the use of raw milk on an affected farm is also restricted. The sale of raw (green top) milk and the production of any milk products from unpasteurised milk on the affected farm or using milk from the farm is prohibited until the farm is officially cleared of infection.
Cattle to Cattle Spread
There is evidence that more intensively farmed cattle are more at risk from the disease (Griffin et al., 1993). The lower stocking rates in organic farming may be beneficial in reducing the risk of TB infection. The prevention of contact between cattle on neighbouring farms is very important. Sound fencing to stop nose to nose contact and barriers in gateways to stop contact with passing cattle are important. Contract reared cattle should be kept away from the herd.
A closed herd system and breeding own replacements should help to keep the disease away from the farm. Bought-in animals should be kept away from the main herd. The TB status of bought-in cattle should be checked by finding out when they were last TB tested. If they need testing before your routine herd test, consider a private TB test. Your veterinary surgeon can advise you on how to do this.
If possible, avoid common grazing. If common grazing is inevitable then skin tests should be synchronised on all farms using the common grazing (MAFF, 1999).
Spread from Wildlife
Even if the local badger population is infected with TB, there are many other factors which influence whether or not cattle become infected. It makes sense to minimise direct contact between cattle and badgers and contact between cattle and areas where badgers live or may have left saliva, urine or faeces.
Keep wildlife out of buildings, especially feed stores. Areas around badger sets should be fenced off to keep cattle out while allowing badgers free access. Badger latrines should also be fenced off for cattle (Hutchings and Harris, 1999). Active latrines are avoided by most cattle until the sward length in the rest of the field has reduced, after which there is an increasing likelihood that active badger latrines are grazed, especially by lower ranking cows (Hutchings and Harris, 1997). Overgrazing fields used by badgers should therefore be avoided. When cutting for hay or silage, grass from badger latrines and field margins should be avoided. Raise feed and water troughs so that their lips are at least 80 cm off the ground.
Dispose safely of badger carcasses found on the farm. Use a facemask and gloves (MAFF, 1999).
It is an offence to interfere with badgers or their sets.
The Krebs report recommends that vaccines against TB in both cattle and badgers should be developed to protect both species (Krebs, 1997; Newell and Hewinson, 1995).