# Regulation (EC) No 999/2001 of the European Parliament and of the Council of 22 May 2001 laying down rules for the prevention, control and eradication of certain transmissible spongiform encephalopathies, Division 8: Where the appropriate authority allows, in accordance with the second paragraph of point 1, the sampling and genotyping of breeding rams in flocks not participating in the breeding programme, the prion protein genotype for the codons 136, 141, 154 and 171 shall be determined for a minimum sample representative of the entire ovine population ..., either:

Extent: E+W+S+N.I.

(a) once every 3 years with a minimum sample of at least 1 560 ovine animals; or
(b) at a frequency and with a sample size ... based on compliance with the following criteria:
(i) the sampling design takes into account relevant epidemiological data collected during previous surveys, including data concerning the prion protein genotype of sheep for the codons 136, 141, 154 and 171 by breed, region, age, sex and flock type;
(ii) the sampling design allows at a minimum to detect a change of 5 % in genotype prevalence over a 3-year period, with a 80 % power and 95 % confidence level.

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Source: https://www.legislation.gov.uk/eur/2001/999/annex/VII/chapter/C/part/1/division/8 (the official version)
Page: https://openlegislation.uk/eu-regulation-2001-999/annex-VII/chapter-C/part-1/division-8
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.