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Ovine Observer

Buying rams? Don’t bring ovine brucellosis into your flock

Trudy Clarke
Department of Agriculture and Food, Western Australia (Katanning)
Email: trudy.clarke@agric.wa.gov.au

Producers are reminded to be careful that they do not buy in rams carrying ovine brucellosis during the coming ram buying season.

Ovine brucellosis is a chronic reproductive disease that causes significant economic loss and can be difficult and expensive to eradicate. Rams purchased from ovine brucellosis accredited flocks are at lower risk of carrying the disease.

Ovine brucellosis can infect rams from all breeds of sheep. The infection is subtle and usually unnoticed at first, but becomes chronic.

The causative bacteria, Brucella ovis, permanently localises in the epididymis and genital tract of one or both testicles. Over time palpable lesions may develop at these sites but some infected rams may never show obvious lesions. Once a ram becomes infected it remains infected for life and will perpetuate the disease in a flock.

The disease is spread in infected semen, either between rams via infected ewes at joining, or by homosexual activity when rams are housed together. Ewes, once infected, will lose their embryo and can remain infected for up to four months, so can spread infection to other rams.

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The testes of rams carrying ovine brucellosis often still look normal

Ovine brucellosis causes significant production and economic loss in infected flocks by reducing lambing percentages, extending lambing seasons, premature ram failure and increased ram turn over. It may take up to two months after infection for blood tests to detect rams infected with ovine brucellosis. DAFWA recommends rams be isolated for two months and then checked for the disease before they are introduced to your flock.

Eradication of ovine brucellosis from a property can be costly and time-consuming. To detect and cull infected rams requires blood testing at two-monthly intervals, usually for four rounds of testing or more. Alternatively, all rams in contact with infected rams, perhaps all rams, need to be culled to remove the disease.

DAFWA administers a voluntary Ovine Brucellosis Accreditation Scheme for ram breeders. Registered veterinarians inspect and advise on property biosecurity, undertake inspection, and blood test rams on studs participating in the scheme. Lists of accredited flocks are available on the Ovine brucellosis page. 

Information about the disease and the application to join the scheme and other accreditation scheme forms are also available on the webpage.

DAFWA recommends asking ram vendors for a National Sheep Health Statement to provide confirmation of their ovine brucellosis accreditation status, as well as important information about treatments and vaccinations and other endemic diseases including their ovine Johne’s disease surveillance.

For more information contact Dr Trudy Clarke, Veterinary Officer, Katanning on +61 (0)8 9821 3254.