Changes to Council Directive 74/63/EEC of 17 December 1973 on the fixing of maximum permitted levels for undesirable substances and products in feedingstuffs
EU Directive 1974/63
Made by Third Commission Directive 83/381/EEC of 28 July 1983 amending the Annex to Council Directive 74/63/EEC on the fixing of maximum permitted levels for undesirable substances and products in feedingstuffs
From legislation.gov.uk's record of changes, the official one: see it there.