SIR, – A recent email from SAC’s maedi visna scheme informed us that we must now test bought-in MV accredited animals within 6-12 months of purchase. It also strongly advised that purchased MV-accredited sheep should be tested immediately.

The reason given is the number of bought-in sheep being identified as MV reactors in routine flock tests. If the motive for issuing the new rules is the protection of flock health, then the warning to test MV-accredited sheep should be issued to all buyers of MV-accredited stock.

It seems, now, that we can no longer have any confidence at all in the MV-free status of sheep sold at MV-accredited sales and it certainly calls into question the integrity and credibility of the MV scheme.

Eight years ago, the Beltex Sheep Society council met with MV scheme staff to air various complaints about false-positive MV tests and lack of support for breeders trying to regain their MV status after a MV breakdown. They also highlighted several instances of bought-in sheep and sheep which had been off-farm, had been the sole reactors in so-called ‘ breakdowns’ in MV scheme flocks and had been re-tested privately with negative results.

The SAC representatives had no answers and it seems they still have no answers, or any solution to the problem of false-positive tests. It is surely not beyond the realms of scientific possibility that bought-in sheep, shared tups, or sheep that have been off-farm for flushing or semen collection, meet the challenge of a new environment by producing antibodies to the different strains of bacteria and viruses they encounter.

This may well show up as a false-positive in the highly-sensitive MV ELISA test. It’s nothing new and SAC have known about it for a long time, but there’s no PCR test in place to confirm positive ELISA tests.

The majority of MV scheme members join only because MV accreditation is a requirement for entry to their breed society sales. Gaining and preserving MV-accredited status comes at a considerable expense, but SAC are now saying that MV certificates are not worth the paper they’re printed on and we have to spend more money on MV tests.

They have got to be joking! If by chance, it’s for a research project, the new tests should be free of charge.

There are several cattle health scheme providers, all using ELISA tests at competitive prices, but SAC has the monopoly on MV scheme testing and can set the price it sees fit. Is there any reason at all why this monopoly should be preserved at sheep breeders’ expense?

Why should other accredited laboratories be denied the opportunity to offer MV testing or even their own MV schemes?

SAC have known for years that bought-in sheep were being identified as MV reactors, albeit false positive reactors, but why is it only now that supposedly MV-free sheep must be considered a risk to flock health, and MV-accredited status?

When farm incomes are coming under such enormous pressure, it really is taking the Mick to ask breeders to dig even deeper to finance a health scheme that no longer offers buyers any assurance of health status.

Mrs Maimie Paterson

Upper Auchenlay,

Dunblane.