Bovine Johne's Disease: Alternatives for Affected Land

Note Number: AG0920
Published: March 2003
Updated: July 2009

 

Choosing the right alternatives for bovine Johnes disease (BJD) affected land can offer owners not only an improved BJD status, but also worthwhile income.

Under national guidelines for the control of BJD, there are many ways in which BJD affected land can be managed to achieve decontamination. These options are not widely understood by vendors, purchasers and agents, and can result in unnecessary devaluation of the land. There are several options for removing the 'Infected' status on land, including:

Option 1

Destock and decontaminate

The bacteria that cause BJD can survive on land, after infected cattle have been removed from the property, for up to 12 months. The national BJD Standard Definition and Rules state that land will be deemed to be no longer contaminated if it remains destocked of all susceptible species (cattle, alpaca, deer, goats) for 12 months….. the Chief Veterinary Officer (CVO) may, however allow grazing of susceptible species which are not regarded as shedding infection during the decontamination period.

In practice, this could be achieved by:

Removing the infected herd from the property, with the aim of leaving the land destocked of susceptible species for 12 months. The land could, for example, be used for growing crops or grazing sheep. At the end of the decontamination period, the farm could be restocked with Non-Assessed cattle, or cattle from Monitored Negative herds, without affecting their BJD status; or

With CVO approval, short-term grazing of cattle less than 2 years of age from Non-Assessed herds. These cattle must be sold directly to an abattoir for slaughter at the completion of the period. The land could then be restocked with Non-Assessed cattle, or cattle from Monitored Negative herds, again without affecting their BJD status; or

With CVO approval, and in situations where it is considered that the level of contamination of the land is likely to be very low, a new adult herd with a documented Non-Assessed status could be run on the property. For example, a NA milking herd (no cattle less than 12 months of age) could be run on an infected dairy property providing that they did not calve on that property or that calves were removed from their dam within 12 hours of birth and were raised off the property. For 12 months the herd would have a Suspect status and would then revert to Non-Assessed, provided there was no suspicion of BJD during that 12 months. Beef calves could remain on their dams but would have to be sold for slaughter prior to reaching 2 years of age.

During destocking, boundary fencing should be maintained to ensure no cattle stray into the property. Drainage and waste-water spillage from neighbours should be prevented to ensure BJD bacteria are not washed onto the decontaminating property.

Option 2

Progressive destocking

This option involves culling the original herd over a number of years and replacing it with purchased heifers or cows. All cattle bred on the property would be sold prior to reaching two years of age and replacement breeders purchased when over the age of twelve months, preferably from low risk herds. The original cattle are culled from the herd. If 20% of cattle are culled each year, the entire original herd can be replaced within 5 years.

Option 3

BJD Test and Control Program

Undertake an approved testing program and management practices to limit the spread of BJD in the herd. On achieving a negative whole herd test, at least 12 months after the last known infected animal was removed from the herd, the status will change to Restricted. A further two whole herd negative tests at 2 yearly intervals (ie 5 years after the last infected animal was removed), would result in the herd status advancing to Tested to CattleMAP Standard. The herd would then be eligible to apply to join the CattleMAP.

Option 4

BJD Control Program

Comply with all the requirements of the BJD Control Program Agreement. Five years after the last case, the herd status will change to Suspect. The property/herd will remain Suspect indefinitely until the herd undergoes an approved testing program.

In summary, there are a number of options for producers seeking to decontaminate their land, and programs can be tailored for individual circumstances. Before taking any action, the possible implications of testing, control and/or decontamination programs should be discussed with DPI Animal Health staff, your veterinary practitioner and legal adviser.

Further information

For further information about alternatives for BJD affected land contact Animal Health staff at your nearest DPI office or on the DPI external web site.

Acknowledgement

This Agnote was deveopled by Sally Ridge, March 2003.

It was reviewed by Iain McLaren, Biosecurity Victoria. July 2009.