It appears there is a common perception among producers that ovine brucellosis (OB) is an issue of the past. If you hold this view, unfortunately you are misinformed. A recent survey of OB in the Riverina by Senior District Veterinarian Dan Salmon found 31% of flocks (109 of 353) were positive for the disease.
Ovine brucellosis is a bacterial disease acquired by rams. Infected rams are either subfertile or infertile, which causes moderate to severe reductions in the pregnancy rates of ewes. It is common that a recently infected mob will have a 30% reduction in pregnancy/lambing rate. This alone is an enormous cost to the business, before even considering the loss of infected rams needing replacement.
On the other hand, once OB is eradicated from a flock, it is common for ram percentages to reduce by up to 30%, joining periods to reduce by up to 50% and lamb marking percentages to increase by 30%. It is clear this is a disease worth managing out of your sheep flock.
To get an idea whether there is OB in your flock, you need a picture of the ewes' fertility profile. This starts with pregnancy scanning, followed by lambing percentages, marking percentages and weaning percentages. If there are significant variations in these numbers, or your scanning performance is sub-par, this should be investigated.
There is no treatment or vaccination for rams already affected with the disease, therefore it is prudent to:
- Have sound farm biosecurity – good fencing, ram paddocks etc.
- Communicate with neighbours regarding stray rams
- Only source rams from accredited OB-free flocks
- Don’t buy rams from saleyards or dispersal sales unless you have checked the relevant status and done your own risk assessment
- Know your own flock – learn to palpate your own rams or get a qualified vet to help
If you'd like help identifying and managing OB in your flock, give us a call.
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