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Why control ovine Johne's disease? | AG1127 |
Chris Hourigan, Bendigo
Febuary 2005 |  |
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To date, less than 1% of Australian flocks are classified as either ‘Infected’ or ‘Suspect’ for ovine Johne’s disease (OJD). Models predict that OJD will spread extensively if left uncontrolled. Controlling OJD on individual farms and nationally is beneficial to Australia’s sheep industry.
Effects of OJD
Lost production
The major economic effect of OJD is the increase in mortality within a flock. Annual mortality rates of over 15% of sheep have occurred in flocks that have been infected for some years. Sheep can show signs of OJD at 2 years of age, decreasing wool and meat production.
Fertility rates can fall, while susceptibility to other diseases such as internal parasites can increase. Cull rates may need to increase to remove high-risk mobs.
Extra management costs
These include vaccination against OJD, costs involved with improved nutrition and parasite control, and increased fencing costs.
Controlling OJD can assist in maintaining a healthy flock
Market losses
To reduce the risk of spread to other flocks, trading options for owners of infected flocks may be limited.
While there are currently minimal restrictions on the export trade of meat and other livestock products, access to live sheep export markets may be restricted. Access to interstate markets may also be restricted.
Property values
The presence of OJD constitutes a potential restriction on land use and must be disclosed under Section 32 of the Sale of Land Act (1962) when land is sold. This may have a negative impact on property values.
Disease spread
Flocks owned by neighbours and trading partners can be at risk of infection if OJD is left uncontrolled. An infected flock Property Disease Management Program (PDMP) aims to reduce the risk of OJD spreading by water run-off, and straying sheep.
Public health
Research to date has failed to substantiate a link between Johne’s disease in animals and Crohn’s disease in humans.
Why manage OJD on the farm?
By developing a Property Disease Management Program (PDMP), owners of infected flocks reduce the impact of OJD in their flock, minimise the risk of spreading disease to neighbouring flocks, and may access trading options for low risk sheep.
Vaccination is proving to be very useful in assisting control the spread of OJD within a flock, and if used correctly as a management tool, will allow an affected enterprise to resume trade over a period of time.
Financial assistance measures are available to assist with managing OJD. Financial subsidies are available to obtain professional advice for the development of a PDMP, for vaccine and to undertake flock profile testing.
Owners of flocks that are infected with OJD and undertake no appropriate management measures may, over time, experience heavy losses as the level of infection within the flock increases.
Further Information
Further information about OJD can be obtained from animal health staff at your nearest DPI office or on the DPI web site: http://www.dpi.vic.gov.au/farming/OJD
This publication may be of assistance to you but the State of Victoria and its officers do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.
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