Control Options for Ovine Johne's Disease Infected Flocks		AG1082
Peter White, Benalla Updated: September 2006
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There are a range of management options available to assist in the control of ovine Johne’s disease (OJD) in infected flocks.

Managing OJD

In the first few years after OJD enters a flock, it may cause very few deaths. Losses usually become more significant with time. When OJD has established in a flock, death rates due to OJD alone are commonly around 2-3% a year. Some flocks, however, have experienced much higher losses.. These flocks tend to have had OJD for many years.

Producers should consider all options carefully, particularly in terms of the long-term effect on the farm business. Financial assistance of up to $3000 is available for professional advice to assist producers make informed decisions on the management of OJD (refer to Agriculture Note: Financial assistance measures for ovine Johne’s disease in Victoria).

Factors that should be taken into account include:

• the financial assistance currently available
• current and expected stock losses
• the trading implications for the business, and
• the likelihood of being able to successfully manage the effects of the disease.

A Property Disease Management Program (PDMP) should be carefully designed for each individual property. The main principle is to reduce the exposure of sheep (including neighbouring flocks) to OJD bacteria. This applies to all sheep, but especially younger animals. Methods to control OJD include: Removing sheep showing obvious signs of OJD as soon as possible, to reduce contamination of pastures. Keeping animals in good health by controlling internal parasites, ensuring adequate nutrition and avoiding other forms of stress. Considering culling high-risk mobs that are more likely to contaminate pastures.

Good grazing management can assist control OJD

Vaccinating against OJD can be very beneficial. It significantly reduces death rates and the numbers of bacteria shed by infected sheep. A subsidy is currently available. Conducting an Infected Flock Profile test will assist in identifying high-risk and low-risk groups within the infected flock. Low-risk sheep can be used as a breeding nucleus as well as useful buffers between neighbouring properties. Grazing management strategies to avoid high stocking rates on very short pastures. Cropping or grazing cattle on land contaminated with OJD bacteria, can reduce contamination. Avoiding lambing on heavily contaminated areas. Vaccinating replacement sheep and weaning onto lower-risk pastures. These include areas that have not been grazed by high-risk mobs. OJD bacteria survive longer in damp shady areas, such as around dams, springs or swamps. Avoiding yarding low-risk sheep in heavily contaminated yards. If possible, carry out routine procedures such as marking, drenching and jetting in portable yards. Bring low risk sheep through yards first if portable yards are not available. Crutching or shearing before lambing to reduce the amount of manure on the udders and legs of infected ewes. Weaning early to separate lambs from ewes. Avoiding water supplies that are heavily contaminated with manure from high-risk sheep.