One in 10 WA sheep have OJD: DAFWA

One in 10 WA sheep have OJD: DAFWA


THE Department of Agriculture and Food (DAFWA) predicts 10 per cent of WA's sheep flock is infected with Ovine Johne's Disease (OJD).


THE Department of Agriculture and Food (DAFWA) predicts 10 per cent of WA's sheep flock is infected with Ovine Johne's Disease (OJD).

And DAFWA field veterinary officer Dr Anna Erickson believes many of cases are yet to be detected.

Dr Erickson presented information about OJD at the WAFarmers Sheep Health Workshop at Muresk last week.

OJD is a wasting disease that affects mainly sheep, caused by a strain of bacteria that affects the intestines and prevents absorption of nutrients.

The bacteria are shed in the faeces of infected animals and can survive for up to 12 months on shaded pasture, and 24 months in water.

Dr Erickson said the disease's long incubation period of two to three years made it difficult to detect and easily transferred.

"One of the big problems with OJD is that apparently healthy sheep can be carrying bacteria in their system, so you can buy them in and they'll go on to contaminate the property," she said.

"They've got the bacteria in their system, it's building up to the point where it's actually going to make them sick but they don't give you clinical signs until they're four years old."

Dr Erickson said it was common for the disease to go unnoticed on an affected property for five to 10 years.

"It can build up to a really high number of losses before people realise they've actually got a really big problem because it's happening in a trickle," she said.

Approximately 120 properties are suspected or known to have been infected with OJD in WA.

Dr Erickson said the properties most at risk of spreading OJD were the 70 to 75pc of properties infected with the disease that did not yet know it.

"It's the people who have it but don't know they've got it that are your risk, people who know they've got the disease will tell you," she said.

Dr Erickson said properties in high rainfall areas with permanent pastures and high stocking rates are most often affected.

"All of those things are very helpful for the bacteria in terms of spread and establishment and it being able to persist in the environment," she said.

"Obviously if you've got more sheep in a smaller area it's going to move around between that much more and there's that much more contamination in the paddock."

Dr Erickson said the best way to avoid the disease was to run a closed flock, vaccinate sheep and buy sheep carefully.

"If you are looking at buying sheep look for a property that has a testing history, look for a property that's vaccinating and, after that look for a property in the really dry areas."

She said maintaining boundary fences, and fencing off water courses was also recommended, along with crop rotation.


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