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Face-to-face with BJD: One farmer's cautionary tale

AustralianFarmers speaks with cattle breeder Rod Hoare, to understand his personal experience with Johne's Disease and how his biosecurity planning and record keeping saw him awarded the 2012 Biosecurity Farmer of the Year.

There has been much discussion in recent months on Johne's Disease and the new requirements for Australian beef producers. It highlights the importance of biosecurity planning and how preparedness can prevent or minimise harm.

After a career spent working with NSW Department of Primary Industries, veterinarian Rod Hoare retired in 2005 to breed stud cattle.  Rod and his partner Helena Warren, a nutritionist and riding instructor, had been developing their property, “Cadfor”, at Binda which they purchased in 2001.  Their herd of stud Murray Grey cattle, established in the 1970’s, was moved to Binda from the Picton area.

Rod says that starting with a bare block, with minimal infrastructure, was an advantage in planning the property to reduce the risk of introducing pests and diseases.  Fences and roads were laid out so that traffic was controlled.  Visitors were directed to a parking area and visiting horses were kept away from resident horses. 

Most of the existing boundary fences were not in great condition so an electric fence was erected about 5 metres inside the boundary to strengthen the perimeter and to allow planting of tree lines.  One of the biggest biosecurity risks at Cadfor is the introduction of Serrated Tussock.  The long grass and the trees in the peripheral buffer greatly reduce the entry of wind borne weeds.

The Murray Grey herd had been kept as a closed herd but with the purchase of a larger property additional seedstock were sought.  Rod was concerned about the possibility of introducing cattle affected with Bovine Johnes Disease (BJD).  Although the stud was not in the Market Assurance Program (MAP) the herd had been tested twice for BJD with negative results.  

In 2001 two stud cows were purchased from an auction at a local Murray Grey stud that was in the BJD MAP at the highest level of freedom, MN3 (Monitored Negative 3).  However a year later Rod was advised that the stud of origin had a BJD reactor which made the two purchased cows of “Suspect” status.  The cows were held in isolation and tested negative.  The suspect stud retained its MN3 status so a presumption was made that the test reactions were false positives.

On-farm biosecurity practices at 'Cadfor'
Directional signs, double fencing and holding paddocks: some of the on-farm biosecurity practices in place at "Cadfor"

In 2005 eight further cows were purchased at auction at the local stud together with calves at foot.  However, in 2007 cattle at the local stud gave further positive tests which were confirmed to be BJD.  These results were not conveyed to Rod and Helena at the time.

In 2008, Rod and Helena tested their herd for BJD with negative results, before entering the BJD MAP.  When they submitted their application to join the MAP they had to advise of recent introductions. The purchase of the cattle raised alarm and they were then advised of the BJD positives in the MN3 herd from which they had purchased cattle. The Cadfor herd was placed in quarantine and the cattle were to be sold for slaughter only.

Unfortunately, in the three years since their purchase, six of the eight cows had been sold and were not available for testing to demonstrate their freedom from BJD. The DPI made an assumption that these cows could have been infected and had transmitted the disease to cattle in the Cadfor herd.  The DPI estimated that there was a 94 percent chance that one or more of the purchased cattle was infected with BJD.  The recommendation was that the whole Cadfor herd should be slaughtered. 

To understand the level of risk that their herd was faced with, Rod needed to know the level of infection in the source herd.  He asked the DPI how many positive tests had been found and what strain (cattle or sheep) was involved?  He also asked if the herd had a confirmed case in 2001 how was a level of MN3 credited to that herd by 2005.  Also if a positive test was obtained in 2007, why did it take over 12 months for purchasers of cattle at the sale to be notified?  The DPI refused to provide any information citing confidentiality.  

The recommendation was that the whole Cadfor herd should be slaughtered.
AustralianFarmers

Rod was unwilling to sacrifice the herd which he and his family had been breeding for over 40 years. None of the Cadfor cattle displayed any signs of the disease or reacted positive to laboratory tests.  However, he wanted to be 100 percent sure that his herd was free of BJD. 

Rod used his detailed record keeping to pin-point which stock had come in contact with the purchased animals, what paddock they’d been in and where they had moved to and the contact had with other cattle. Rod concluded that 23 animals had been in contact with purchased cows.  He accepted that, if any of the purchased animals were infected, any of the 23 could have the disease. 

Laboratory tests can be ineffective due to the disease’s very long incubation, and so Rod made the decision to slaughter 23 animals in the herd that may have been a risk. However, while they were testing negative it was possible to retain their heifer offspring to retain their bloodlines.  So the herd was split into two; a clean herd with no risk of BJD and a BJD risk herd. 

The BJD risk herd was tested at six monthly intervals.  Heifers were transferred from the BJD risk herd to the clean herd when the BJD risk herd had at least two successive negative tests.  After two years the BJD risk cattle were sold and the Suspect status was lifted.

With the quarantine lifted all was not over. The financial cost of having to sell his cows for slaughter only cost Rod an estimated $800 per head, an issue that also fell to the bulls that were also sold to slaughter. The incident created a cloud over the stud’s reputation and when coupled with the stress of managing the incident it was a very difficult time.

The story at Cadfor is typical of many cattle properties impacted by Johnes Disease. It highlights the importance of on-farm biosecurity practices, and the impacts when things go wrong.

Under new arrangements for managing Johnes Disease, producers are more responsible for managing their own risks. Get the latest information and resources to complete your farm biosecurity plan (to comply with the J-BAS program) from Animal Health Australia here.

 

Chris Gillies is a freelance writer and agricultural journalist based in Sydney.

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