18 February 2000

SHETLANDS LEAD THE REST

THE SHETLAND Islands are leading the rest of the country in scrapie control programmes.

The Islands native sheep – the Shetland – could be the first breed to eradicate scrapie, having embarked on a comprehensive flock health programme in 1984.

Its aim is simple; to eradicate scrapie and improve public confidence in sheep meat, says SAC Thursos Sandy Clarke, who believes scrapie would have been less of an issue had it not been for BSE.

The scheme got off the ground with help from Shetland Islands Council who funded the project to help banish the disease. The project began by recording breeding information of ewes and lambs within pedigree breeding flocks. From then on, any sheep which developed scrapie could be identified and culled, along with their offspring.

About 100 pedigree breeders joined the Shetland Flock Health Scheme set up to tackle the problem, adopting some draconian measures to achieve its goal.

Initially this meant culling offspring of ewes with clinical scrapie, says Shetland producer Andy Abernethy, Clousta, Clousta Bixter, where he keeps 660 pedigree Shetland ewes.

This began to have an impact on the disease, but according to Mr Abernethy, the real breakthrough in control came when genotyping was introduced.

"To begin with you werent advised to cull offspring of a tup that had scrapie because you needed to have good records to trace them all." In addition, there was some contention about how much influence tups played in transmitting the disease.

Tups major factor

"We always felt tups were a major factor in spreading the disease and this has been proved right," he adds. Before genotyping began, Mr Abernethy didnt think he could rid his flock of the disease.

"Blood testing tups was a big break through. Now we are not breeding from infected tups, incidence of disease has dropped greatly."

Before introducing control measures, scrapie had a big impact on flock income. Most ewes contracting scrapie would be two or three-years-old. "From a financial position, losing ewes in the prime of their life is a big loss," he says. Genotyping and the scheme have helped reduce losses, and in some flocks, eradicate scrapie.

In the case of Shetland sheep, genotyping is fairly straightforward, says Dr Clark. Since this has been introduced to the control programme, tups must be genotyped to ensure only non-susceptible strains are bred from.

He believes moves to use only non-susceptible strains of rams has prevented the disease remaining at a low level on Shetland. "It probably would have grumbled on for longer without using genotyping to control it. We can now hopefully rid the Islands of the disease and the agent that causes it."

This means the group will continue recording and blood testing to ensure scrapie is eradicated.

How a blood test can give information about a sheeps susceptibility to scrapie. But understanding results is still a hard task. Source: SAC

RISKGROUP MEANINGS

R1 Indicates a very low risk of scrapie in the individual sheep and a low risk in the first generation progeny.

R2 Indicates a low risk of scrapie in the individual sheep and a low risk in the first generation progeny.

R3 Indicates a low risk of scrapie in the individual sheep but some progeny may be at risk depending on the genotype of the other parent.

R4 Indicates that scrapie may be occasionally recorded in this genotype and a higher proportion of R4 progeny are likely to be at risk compared to R3 progeny.

R5 Indicates sheep at greatest risk from scrapie.

Source: SAC