Conducting an archaeological dig in the papers which had lurked for a while at the end of the dining room table, turned up a MAFF leaflet "Action on Animal Health and Welfare" "Scrapie. Advisory Notes for Farmers" I noted that it warned that "little is known about the interaction between the animal's genotype and the different strains of scrapie. It is possible that an animal bred to be resistant could carry the disease without showing signs and be a source of infection to others." The copyright was 1999 so I had a look at what the DEFRA website http://www.defra.gov.uk/ says.
These are some extracts found under Animal health and welfare
"Selective breeding of sheep flocks to increase resistance to transmissible spongiform encephalopathies (TSEs) is now possible. This will be a major focus of the National Scrapie Plan (NSP) currently being developed to eliminate TSEs from British sheep and which is subject to a consultation exercised being carried out by MAFF and the Agriculture Departments of the Devolved Administrations in Great Britain. There is still however a lot to learn about the interplay between sheep genotypes and scrapie including whether resistant animals can still carry infection and not develop the disease. (See the European Commission Scientific Steering Committee's opinion on 'The policy of breeding and genotyping of sheep, i.e. the issue of whether sheep should be bred to be resistant to scrapie'.) Evidence from ongoing MAFF experiments indicates this may in fact not be the case. This will be kept under close review as the NSP develops."
There follows a summary of experimental findings, with the conclusion:
"Thus, because it seems as if resistance is not absolute, breeding policies that aim to produce one particular genotype may produce a population that is resistant to one strain of scrapie, but render the flock more susceptible to other strains.
"So far, only one sheep that was homozygous for arginine at codon 171 has ever been diagnosed with scrapie. Breeding sheep that are homozygous for arginine at codon 171 may therefore prove to be beneficial in the effort to increase scrapie resistance, but gene frequencies in some breeds will inevitably render some breeding programmes difficult if other desirable genetic characteristics are not to be lost by selecting for scrapie resistance."
The ECSSC document is at:
It debates, among other things, whether it would be preferable to breed for scrapie susceptibility, so that any affected sheep can be identified or for resistance, with the risk of favouring carriers.
The justification offered by Elliot Morley for the draconian measures relating to scrapie in the Animal Health Bill has been the lack of take-up by sheep keepers of the voluntary National Scrapie Plan. The first stage of this was launched only to breeders of purbred pedigree flocks registered with a recognised breed society - in July 2001!!! One can't help feeling that the attention of even these sheep keepers was elsewhere.
National Scrapie Plan
"The first stage of the Ram Genotyping Scheme is the Expression of Interest exercise. This was launched on 19 July 2001 when breeders of purebred pedigree flocks registered with a recognised breed society were issued NSP Expression of Interest forms and leaflets to register an interest in the National Scrapie Plan. Application forms and a NSP Schemes Brochure[659Kb] are now being issued to breeders who returned the Expression of Interest form and blood sampling visits are now taking place."
Not on my farm!