AN INCREASING prevalence of ovine Johne's Disease in southeast Australia has prompted a warning to sheep producers to vaccinate all breeding ewes.

The warning, from both the Sheepmeat Council of Australia and WoolProducers, coincides with reports that the increased level of flock infections is jeopardising trading zones in southern NSW and Victoria.

Under current zoning arrangements, flocks in western Victoria and southwest and western NSW are rated as having low prevalence of OJD, with a credit score of 4 under the Assurance Based Credit scheme. South Australia also has a score of 4.

The rest of Victoria is of medium prevalence, with a less-favourable score of 2, while the NSW's Southern Tablelands has a high prevalence, with a zero credit score.

Producers in a particular zone can only introduce sheep with a comparable or higher ABC score.

ABC flock scores can be increased by vaccination or participating in a market assurance program.

Sheepmeat Council president Kate Joseph this week conceded current arrangements were struggling to keep OJD, a wasting disease, under control.

"My advice to producers is to vaccinate all breeders and other sheep retained beyond one year," Ms Joseph said.

"There is certainly no need to vaccinate terminals."

And while sheep can be vaccinated at any age, Ms Joseph said lamb marking was the preferable time for providing maximum protection and because lambs were much easier and safer to handle and vaccinate.

"Lambs vaccinated before 16 weeks of age are protected from bacteria on contaminated pasture and therefore attract extra credit under the ABC scheme," Ms Joseph said.

He said results from an abattoir monitoring last year indicated a third of southern NSW flocks were affected by OJD.

Abattoir surveillance in June last year found 567 infected flocks in Victoria.

And while the latest surveillance data from Animal Health Australia has not yet been released, reports indicate a deteriorating situation, prompting suggestions that a proposed review of zones scheduled for 2012 could be implemented within the next few months.

Such a review could jeopardise the trading opportunities enjoyed between western Victoria and the Riverina.

WoolProducers president Don Hamblin is also urging a Gudair vaccination, to not only reduce flock mortalities but also boost a flock's trading opportunities.

A Gudair vaccination costs about $2 a sheep.