Genetic resistance to transmissible spongiform encephalopathies (TSE) in goats

Breeding programmes to promote resistance to classical scrapie, similar to those for sheep in existingtransmissible spongiform encephalopathies (TSE) regulations, have not been established in goats. TheEuropean Commission requested a scientific opinion from EFSA on the current knowledge of geneticresistance to TSE in goats. An evaluation tool, which considers both the weight of evidence andstrength of resistance to classical scrapie of alleles in the goatPRNPgene, was developed and appliedto nine selected alleles of interest. Using the tool, the quality and certainty of thefield andexperimental data are considered robust enough to conclude that the K222, D146 and S146 allelesboth confer genetic resistance against classical scrapie strains known to occur naturally in the EU goatpopulation, with which they have been challenged both experimentally and underfield conditions. Theweight of evidence for K222 is greater than that currently available for the D146 and S146 alleles andfor the ARR allele in sheep in 2001. Breeding for resistance can be an effective tool for controllingclassical scrapie in goats and it could be an option available to member states, both at herd andpopulation levels. There is insufficient evidence to assess the impact of K222, D146 and S146 alleleson susceptibility to atypical scrapie and bovine spongiform encephalopathy (BSE), or on health andproduction traits. These alleles are heterogeneously distributed across the EU Member States and goatbreeds, but often at low frequencies (<10%). Given these low frequencies, high selection pressuremay have an adverse effect on genetic diversity so any breeding for resistance programmes should bedeveloped at Member States, rather than EU level and their impact monitored, with particular attentionto the potential for any negative impact in rare or small population breeds