Commission Regulation (EC) No 921/2004 of 29 April 2004 amending Regulations (EEC) No 2191/81, (EEC) No 429/90 and (EC) No 2571/97 to take account of the requirements of Council Directive 92/46/EEC laying down the health rules for the production and placing on the market of raw milk, heat-treated milk and milk-based products