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Controlling Bovine TB

Controlling Bovine TB

What is TB?

Bovine TB is an infectious mainly respiratory disease caused by a type of bacteria called Mycobacterium bovis. It has a thick cell wall which makes it a hardy and resistant organism and research has shown it can live in manure for up to 6 months.

The main route of infection is by breathing in droplets of mucus or sputum when in close contact with infected cattle or wildlife. Other routes include consuming food or drinking water or grazing grass contaminated with infectious material which can be sputum, mucus, milk, urine, faeces or pus from infected animals.

  • It is mainly a disease of cattle but can affect a range of other mammals.
  • Cattle to cattle transmission of TB resulting from cattle movement is one of the main contributors to the spread of TB.
  • Infected cattle commonly do not show signs of TB and will look healthy.

To help in the control of TB there is an on-line TB Hub which is a joint initiative supported by the Agriculture & Horticulture Development Board, Animal & Plant Health Agency, British Cattle Veterinary Association, Defra, Landex and NFU.

This article is a summary of the practical advice given there under a 5 point plan of actions and recommendations:

  •  Restrict contact between badgers and cattle
  •  Manage cattle feed and water
  •  Stop infected cattle entering the herd
  •  Reduce risk form neighbouring herds
  •  Minimise infection from cattle manure

 

Restricting contact

  • By installing sheeted gates rather than barred gates at least 1.5 metres high and with gaps of less than 75 mm on farm yards and buildings and in particular on feed stores. A hard standing of e.g. concrete beneath gates and yard barriers will help to prevent badgers digging underneath to gina access.
  • Electric fencing may also be used to restrict badger access to both buildings and cattle grazing but should not prevent badger access to their setts. Four strands of electric fence wire are recommended at 10, 15, 20 and 30 cm above ground.
  • Consideration should be given to high risk grazing areas such as near setts and fields with badger latrines; these could be fenced off and or grazed with lower risk stock such as sheep
  • Mapping areas of badger activity such as setts and latrines will help with making grazing decisions to avoid high risk areas.

Managing feed and water

  • Pay attention to feed store walls and doors to limit or prevent badger access. Secure bins and silos may be a good idea, if old stores are too expensive to upgrade.
  • Secure silage clamps against badger access such as by the use of electric fence.
  • If feeding and using mineral blocks outside have troughs etc raised as high as possible for cattle to use but to prevent badger access.
  • Do not feed on the ground
  • Water troughs should not be accessible to badgers and stagnant water ponds and ditches should be fenced off to cattle.
  • It is not recommended to feed milk from TB reactors or inconclusive reactors to calves.

Stopping infected cattle entering the herd

  • Check the TB history of a herd before you purchase from it and the date of an animal’s pre-movement test if it was carried out.
  • The longer a herd has been TB free the lower the risk a purchased animal will still have the disease.
  • Pre movement testing regulations in England and Wales require all cattle 42 days and older moving out from annually tested (or more frequently tested) herds to have had a pre-movement test within 60 days of the movement.
  • All cattle 42 days old and over in a yearly testing area must be pre-movement tested before they move from or enter any Scottish herd. All cattle moving from a yearly testing area must be post-movement tested between 60-120 days of their arrival in a Scottish herd.
  • If the herd you intend to purchase from has not had a recent test or the animal was not bred on holding you should consider isolating the animal and carrying out a post movement test.  This should not be carried within 60 days of the pre-movement test as cattle can be desensitised to the test when carried out too regularly and the result will not be reliable.
  • Consider bull hire very carefully as this poses a high risk of TB transfer.

Reducing risk form neighbouring herds

  • Maintain a good barrier perimeter fence to prevent the contact of your cattle with neighbouring herds. A good example is a secure double fence of at least 3 metres apart. To help further avoid grazing adjacent fields if they contain livestock at the same time or when manure and slurry is being spread.
  • Sharing equipment that has contact with livestock such as manure spreaders and handling equipment should be considered a high risk as should share grazing.
  • Avoid watering cattle from streams that flow from neighbouring farms; these should be fenced off to exclude stock.

Minimising infection from cattle manure

  • It is recommended to store manure or slurry away from stock and wildlife and for 6 months before spreading on grassland as after this time there should be few infectious bacteria present.
  • A further 2 month waiting period is advised before grazing cattle or cutting grass following the spreading of these stored manures and slurries. Pay attention when spreading manure and slurry so as not to create aerosols of manure or slurry; this is particularly important in windy weather.

 

Breeding for resistance?

AHDB dairy has published a genetic index to help farmers to breed cows with an improved genetic resistance to bovine TB. It is called TB Advantage and as yet only has data for Holstein cows but longer term work will extend this index to other dairy and beef breeds. This is a long term consideration and can be used together with best management practises summarised above. 

 

TB in Wales

The Welsh Government has launched a new scheme, Cymorth TB that provides free farm veterinary advice following a TB breakdown. 

There has also been a recent change regarding grazing common land as of 31 December 2015. All cattle movements to and from common land now requires a clear pre-movement test.