Johne’s test breakthrough

Traditionally, a test to confirm Johne’s would take three months.

This was because it could only be detected by culturing the paratuberculosis bacteria in the animal’s faeces over this time.

Sydney University Faculty of Veterinary Science farm animal health chairman Professor Richard Whittington said this breakthrough removed one of the great impediments to testing for Johne’s disease.

Although it’s early days, the cost is similar to the current test.

“So we get this massive advantage of rapid turnaround to results at no additional costs,” Dr Whittington said.

The research that developed the breakthrough test was part of a much bigger project (funded by Meat and Livestock Australia (MLA) Donor Company and the peak sheepmeat, wool and cattle industry bodies) to help sheep and cattle producers manage Johne’s disease risk and better control infections, and perhaps even eliminate the disease over time.

MLA reported that in addition to a 10-year study monitoring the effectiveness of an ovine Johne’s disease (OJD) vaccine, other projects were investigating environmental factors influencing the disease and its cost to sheepmeat processors.

The main one was a $6.4 million project led by Dr Whittington, which sought a basic understanding of how the Johne’s disease bacterium behaved, how it interacted with the host animal, and what science could take advantage of in those interactions to develop better testing methods and vaccines.

“This project has both a short- to medium-term focus and long-term goals,” Dr Whittington said.

“In the short term, we aim to develop tools for immediate application, such as new diagnostic tests and novel predictive tests that can be used to select resistant and susceptible livestock, and tools to improve the safety aspects of the current vaccine.

“Other findings will have a long-term focus, such as developing more economical vaccine efficacy testing methods.”

MLA animal health and biosecurity project manager Johann Schroder said the new test would allow producers to more quickly adopt corrective or remedial management strategies.

“The more quickly you can get a Johne’s disease diagnosis, the more quickly you can stop the further spread of the disease,” Dr Schroder said.

But, Dr Schroder said although the test cut the delays associated with a culture test, it was not foolproof.

“Producers must work closely with their relevant veterinary services to interpret test results at a herd/flock level, and then properly deal with Johne’s disease,” he said.

There are two different strains for sheep and cattle.

The DNA is a little different, but the disease behaves in a similar way in both sheep and cattle.

Ovine Johne’s disease (OJD) is a fatal, wasting disease in sheep that causes the lining of the bowel to thicken and reduces food absorption.

The average time from onset of clinical signs to death was from six weeks to three months although most sheep do not show signs of OJD for a long time, from months to years, after becoming infected.

Bovine Johne’s disease (BJD) on the other hand was often seen in dairy herds rather than beef herds.

Similar to OJD, BJD was fatal and caused by the cattle strain of the same bacterium that causes OJD.

THE iconic Carcoar property “Coombing Park” used to be a mixed operation of both sheep and cattle, but with a confirmed test of Ovine Johne’s Disease (OJD) about 15 years ago it changed the enterprise’s production mix.

“Coombing Park” manager George King said while it was not the only factor that caused the The Whitney Pastoral Company to move out of sheep, the disease was certainly a big concern at the time.

“Having Johnes in the sheep flock meant we had to destock for three years to get rid of the infection, but even if we were clean after that time it (Johne’s disease) could still come back again,” he said.

“That’s when he decided to move into just running cattle.”

Mr King said by not running sheep it also cut the cost of production and reduced the number of staff needed on the property.

“For the cattle side of the operation Johne’s is not such a big concern for us now,” he said.

“Our herd is Johne’s free and we only buy bulls from studs

that have a Johne’s free status such as Greg Fuller’s Pine Creek stud (at Bylong) and Col Bannerman’s Kywarra stud (at Blayney).

“Even so, having a test available to the sheep and cattle industry that only takes a week to get the results is a big step forward for producers having to run these tests.”

The Whitney Pastoral Company run 2000 Angus breeders and turn off the progeny each year as weaners.