http://www.defra.gov.uk/news/2006/060308b.htm

On 7 November 2005 the Over Thirty Month (OTM) Rule was replaced with a BSE testing regime for cattle aged over thirty months and born on or after 1 August 1996. This followed acceptance by the Government in September 2005 of advice from the Food Standards Agency (FSA) that a robust testing regime has been developed following a report from an independent group overseeing trials of the proposed system. Cattle born before 1 August 1996 will continue to be excluded from the food chain.