THERE MAY be no proven link between scrapie and BSE, or BSE and vCJD, but the chance that BSE may some day infect sheep and through this route cause CJD in the human population is still the primary justification for the NSP.
However, while the main aim is protecting public health, the secondary aim – and the one which benefits the industry most – is the protection of animal health by eradicating scrapie-susceptible sheep.
To this end, uptake of the NSP since its launch in 2001, in its various forms, has been high, reckons Mike Dawson of the National Scrapie Plan Administration Centre in Worcester.
“The Ram Genotyping Scheme has more than 10,500 member flocks, which have submitted more than 1m samples for genotyping. More importantly, most breeds are making significant progress towards eradicating susceptible genotypes,” he says (see bottom right).
Early next year, this voluntary scheme will be replaced by a compulsory ram scheme which will genotype all purebred flocks and any other flocks selling home-bred breeding rams, says DEFRA sheep TSE policy director Francis Marlow.
However, the breeding requirements under the compulsory scheme will be much more relaxed than under the voluntary scheme, with only sheep carrying the VRQ allele requiring culling (see table).
This change of direction has led some breeders to question the rationale of the NSP, particularly as many have selected sheep for scrapie resistance above and beyond other traits.
“But the previous scheme was voluntary and breeders made their breeding choices freely as business decisions,” says Mr Marlow.
The NSP is not, however, solely concerned with genotyping rams, with the scrapie flocks schemes, both voluntary and compulsory, taking a whole-flock approach.
Under these schemes, flocks with confirmed cases of scrapie genotype their ewes and rams and cull those with susceptible genotypes. Mr Dawson says: “Under the voluntary scheme, open to flocks with a confirmed case of scrapie between July 1998 and July 2004, all ewes and rams are genotyped and susceptible genotypes are culled.
“This culling depends on the type of scrapie affecting the flock,” explains Mr Dawson.
“Where scrapie is affecting sheep with the VRQ allele then sheep of types three and five are culled, although type three ewes can be retained for up to three years.
“But where it is affecting sheep with the ARQ allele then these sheep must also be culled and in the case of ARQ/ARQ sheep must be sent to slaughter.” Compensation is paid for any sheep culled.
“So far, the Voluntary Scrapie Flocks scheme, has 378 member flocks on 204 holdings across the UK,” says Mr Dawson. “But from July 2004 there has also been a compulsory scheme, with any flock experiencing a confirmed case of scrapie required to join.” This scheme has, so far, attracted 96 flocks on 56 holdings, with more than 20,000 ewes genotyped.
“However, under the compulsory scheme, introduced as a result of EU legislation, there is no recognition of the different types of scrapie. Flocks are only able to retain type one and two ewes and must use type one rams.
“These flocks, having culled all other sheep are placed under a three-year restricted period where they can buy and sell type one ewes and rams without restriction. But type two ewes may only be sold for slaughter or into another compulsory scheme flock.”
These restrictions may be difficult to meet for flocks buying in replacements, but they will be given every assistance, says Mr Marlow. “We will pay for genotyping of replacements whenever they”re sourced.”
However, there is a danger the compulsory flocks scheme could result in under-reporting of scrapie cases as producers attempt to avoid the scheme”s burden, he adds.
“To this end, we are in discussions with the EU about a relaxing the rules to make it less onerous and reduce any non-reporting of suspected cases.”
And while the government will continue to fund the bulk of the scrapie schemes, cost sharing will become an ever-increasing feature of the NSP, says Mr Marlow.
“Under the compulsory ram scheme there will be an option to have ewes tested too, but it is likely that producers will pay for sample collection and DEFRA will fund genotype testing.
“Another area for cost sharing may be identification,” he reckons. “If EU proposals are implemented in 2008, all breeding sheep will have to be electronically identified.
“Currently DEFRA pays for EID for NSP genotyped sheep, but there will be little point duplicating EID, so the NSP could use EID devices supplied by producers,” he suggests.
BOX NSP PAST, PRESENT AND FUTURE 1.5m sheep genotyped so far Ram genotyping compulsory soon Cost sharing increasing FResistance increasing PANEL Compulsory ram genotyping what will it achieve? PANEL