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Vets are being urged to make farmers aware of the potential fertility consequences of the virus.
Allister Webb
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Image: Paul / Adobe Stock
Sheep vets have been urged to warn farmers about the potentially long-lasting fertility impacts on rams affected by the bluetongue virus.
New guidance has been issued by Ruminant Health and Welfare (RH&W) and the Sheep Veterinary Society (SVS) ahead of the forthcoming tupping season.
SVS president Phillipa Page said the document was intended to help facilitate practical assessment decisions that recognised the specific challenges posed by the virus.
She added: “Ram fertility needs to be optimal to achieve target conception rates of more than 85% of ewes in the first cycle, so the potential impact of BTV as we approach mating is a significant concern.
“Although rams can eventually recover sperm production following BTV infection, their fertility for the coming season is expected to be very poor and it is highly likely that rams which have been sick will not breed.
“Sperm development takes around 50 days, and recovery of breeding soundness following BTV infection is considered to take up to 100 days, meaning infection can have a long-lasting effect on fertility during the current breeding season.”
Most of the 670 confirmed BTV-3 incidents in Great Britain so far this season have affected sheep either wholly or partly and clinical impacts have been reported to be much more severe than in cattle.
The standard SVS guidance that rams should be physically examined on an annual basis remains in place.
But the new bluetongue advice warns that vaccination and continued vigilance will remain essential even when rams have passed their assessment.
Earlier this week, the National Sheep Association launched a new survey of farmers’ attitudes to vaccination that it hopes will prevent current supply problems recurring next year.
Mrs Page said: “A successful fertility examination is only a snapshot in time. Vets should be making farmers aware that a ram which subsequently becomes infected with BTV may still suffer an impact on fertility.
“Daily checks for clinical signs, using raddles to identify returning ewes and scanning early will therefore be particularly important alongside vaccination and appropriate pre-breeding examination.”
The full document is available via the RH&W website.