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Vet Cows Carlisle

Johnes Disease

Johnes disease is an infectious wasting condition of cattle and other ruminants (including deer, sheep and goats) and is caused by Mycobacterium avium subspecies paratuberculosis (Map). It is closely related to the organism that causes tuberculosis, and Johnes disease is sometimes called paratuberculosis. The disease progressively damages the intestines and in cattle this results in a profuse and persistent diarrhoea, weight loss and infertility. Affected cattle are more susceptible to other diseases such as mastitis and displacement of the abomasum. In the lactation before symptoms are first noticed yield in reduced by an average of 10%, and in the lactation when symptoms are first noticed yield is reduced by, on average, 25%. The disease usually becomes symptomatic at three to five years of age.

Cattle may be susceptible to infection throughout their lives but are most vulnerable by far in the first few months of life.

Infection is usually spread by the ingestion of traces of infected faeces but colostrum can transmit infection and calves can even be infected in the womb.

A bulk tank sample can be used to determine if infected cattle are contributing to the bulk tank.

Control Measure

  1. Replacement heifer calves should only receive colostrum from their own dam. The udder should be thoroughly washed before milking. Use one bucket per calf. Do not feed pooled colostrum to dairy replacements.
  2. Rear young calves where there is minimal chance of their environment becoming contaminated with faeces from adult cattle.
  3. Keep calf pens as clean as possible and clean them thoroughly between calves.
  4. The Johnes organism is tough, surviving for up to one year in the environment. Do not graze young stock on land which has been spread with slurry or manure, or has been grazed by adults, in the last three months. Ideally wait one year. Sheep are a potential source of infection.
  5. Heifer replacements should be fed milk substitute after the colostrum they receive in the first 24 hours. (Milk can be fed but only if it has been treated with a pasteuriser.)
  6. The milk from each cow can be tested through either CIS or NMR as part of the herd test. Four samples are tested per year. This allows the early identification of affected cows so they can be removed from the herd at the earliest opportunity. The cost is about £7.00 per cow per year. The offspring of affected cows should also be culled. A blood test can be used instead of a milk sample.
  7. Maintain a closed herd or buy from accredited sources.
  8. Provide clean piped water.
  9. It is possible to reduce the levels of infections in a herd but this can take many months. It may not be practically possible to completely eliminate infection.