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Johne’s disease in cattle and saleyards

Animal Health Australia (AHA) coordinates the national Johne’s disease (JD) in cattle Framework for Australia’s beef and dairy industries, governments and veterinarians.

JD is caused by the bacterium Mycobacterium paratuberculosis, which lives in the intestines of infected animals and is shed in their faeces and milk.

The bacteria can survive for months in the environment, especially in cool, shady and moist conditions. High temperatures and sunlight shorten the survival of the bacteria, and it dies off more rapidly in material containing urine and ammonia.

Risk assessment

Features of JD and M. paratuberculosis relevant to saleyards

  • Johne’s disease most commonly occurs in cattle in south-eastern Australia.
  • Dairy and dairy-cross cattle present the highest risk of JD infection.
  • The JD infection is much less common in pure beef cattle.
  • JD-infected cattle are usually older than 2 years of age before they start to excrete bacteria.
  • Cattle with advanced JD infection are particularly potent sources of bacteria.
  • Calves are the most susceptible to contracting JD infection.
  • Calves are inquisitive and often lick and suck surfaces and materials.
  • Cattle older than 12 months are relatively resistant to JD infection.
  • The greater the number of infective bacteria an animal is exposed to, the more likely it is to become infected.

Survival of the bacteria in saleyards

Hosing can remove most faeces from a hard surface, and the bacteria along with it.

Drying and exposure to sunlight should further reduce contamination.

Survival of M. paratuberculosis can be reduced by lime, so concrete surfaces may have a similar effect.

If a shaded, soft-floored pen environment becomes contaminated with M. paratuberculosis infected faeces, the bacteria are likely to survive for much longer compared to an outside pen exposed to sunlight and can be hosed out.

(Although contamination is likely to be higher in cattle barns housing infected cows in Europe and North America than in Australia, calves reared in this way are easily infected.)

Although shading of sale pens favours survival of bacteria, ammonia from urine and heat generated by the decay of organic material on the floor may help to kill bacteria and reduce the likelihood of contamination.

If the roof keeps the floor relatively dry, without being dusty, the bacteria may not be as easily transmitted as on a wet and boggy surface.

Risk management

Do not put calves under 12 months (excluding vealers going direct to slaughter) in pens that are contaminated with adult faecal material. This is the key point to managing the risk of spreading JD at a saleyard.

Adult faecal material can also be spread mechanically, by equipment and boots.

How to reduce the risk of spreading JD at saleyards

  • Have dedicated pens for calves up to 1 month of age.
  • Have dedicated pens—or pens that are cleaned out and, where appropriate, covered with new material before use—for aged calves 1–12 months.
  • Clean up calf pens after each sale.
  • Walk calves quickly along laneways contaminated by adult cattle so they have little time to lick and suck hard surfaces.
  • Avoid moving calves along laneways contaminated with faeces from high-risk cattle:
    • aged culls
    • abnormally thin cows and bulls (taking into consideration drought, etc.)
    • adult dairy cattle.
  • Have dedicated pens for these high-risk cattle.
  • Clean up any areas of gross faecal contamination after each sale.
  • Prevent drainage of faecal material or pen washings moving from adult pens into calf pens.
  • Tighten JD risk management practices for breeder sales because breeding cattle present a much higher risk of spreading JD.

See the Australian Johne’s Disease Market Assurance Program for Cattle (CattleMAP) for guidelines to protecting MAP status at sales and exhibitions.

Related links

 

Page reviewed: July 3, 2016