Be wise on brucellosis

The most common pathways for ovine brucellosis transmission are from buying rams through sources such as saleyards or unregistered ram producers, unwittingly purchasing ewes that are infected, or where boundary fences are unsecured and stock can stray.

The disease causes a permanent infection in rams, reducing their fertility, and is spread during joining or from ram to ram. It is caused by Brucella ovis bacteria, which is found in the semen of infected rams, in foetal fluids and in the mammary glands of infected ewes.

Effects include reduced conception rates, with more ewes returning to service, abortion, extended lambing periods and reduced marking rates. 

Increasing levels of brucellosis in flocks have been identified across the entire industry and lending a productive hand to commercial producers is important to rein in the spreading disease, says Crookwell veterinary surgeon, Robert Churchill.

“I don’t think it matters where the impetus comes from, I think it needs to be put out there to the farmers so they become well educated about the disease and the product they are buying,” he said.

“My argument is there is not a lot of money required. If we can educate farmers into doing their own sample testing and doing their own on-farm testing, that would cost them very little. I would also like to see the different breed societies all make testing compulsory for registered studs.”

NSW Stud Merino Breeders Association Limited president Angus Beveridge would like to see other breeds join Merinos when it came to their brucellosis accreditation policies.

NSW Stud Merino Breeders is the only NSW sheep association that upholds a policy of not only having to be ovine brucellosis accredited to sell rams, but also to be accepted as members of the association. 

“It is not mandatory in other states. It has involved a bit of expense for people getting into studs and then also having to maintain it like any other health testing, but in NSW is mandatory to be ovine brucellosis certified before you can be registered as a Merino stud,” Mr Beveridge said.

Mr Beveridge believes there is too much opportunistic buying and use of rams out of saleyards.

“Those rams could be old rams that were borrowed from a neighbour and are used again - they can then spread the disease,” he said.  

However, on a tri-annual testing program, Mr Churchill said a grey area within sale rams also existed where rams under 20 months didn’t have to be tested two years out of three.  

“Sale rams only have to be palpated, they don’t have to be blood tested,” he said. “With the palpating process we might pick it up, (but the) probability is we won’t.”  

Mr Churchill said too often farmers failed to realise they had brucellosis in their rams before it reduced their flock’s fertility.

“The reason for that is rams are such good machines that it doesn’t take many fertile, or non-infected rams to compensate for the ones that are infected,” Mr Churchill said.

In addition, a lot of people were over joining. “We have farmers out there joining at three or four per cent, which is unnecessarily high,” he said.

Mr Churchill said some producers also held a misconception that more rams meant a more effective joining. However, if brucellosis was present, it merely masked the disease’s presence for longer. 

Ideally, a joining rate of one to 1 1/2 per cent rams was enough.

Central Tablelands Local Land Services district vet Bruce Watt said being vigilant about stray rams or stray ewes was incredibly important.

“If you did find a stray ram, you want to make sure you get it tested, because you really need to know what that ram was up to or whether it was infected,” Mr Watt said. 

“It is a really poor decision not to buy rams approved by the NSW Ovine Brucellosis Accreditation Scheme,” he said. “But even that is not infallible, not because you will get it from the accredited flock, but you may actually already have (the disease) on your place.”

For that reason, he said farmers should determine their flock’s status. “Just to say you have been buying accredited rams for the past decade doesn’t mean you don’t have it,” he said. “This happens a fair bit – people can buy clean rams and tip them into their flock and if they have brucellosis already, then it will stay there.

“Buying accredited rams can end up being wasteful – all these good rams you bought end up getting this highly transmittable disease.”

Rachel Gordon of Livestock Biosecurity Network said managing brucellosis should revolve around control strategies and good on-farm biosecurity. 

“Prior to joining, it is advisable to test all rams for ovine brucellosis at least one month out,” Ms Gordon said.  

Biosecurity measures include undertaking a physical examination of rams, including scrotal palpation prior to purchase and requesting a sheep health statement from the vendor.  “Avoid purchasing new rams from saleyards where possible and ensure any new rams are quarantined for an appropriate length of time after arriving on your property,” she said. “(Also) ensure the integrity of your boundary fences to prevent stock from straying or neighbours’ stock from entering your property.”