Sir; Support for the new Chicken Assurance Scheme has been pledged by food retailers and processors, and statements have been made to the effect that anti growth promoters have now been withdrawn from the raising of British poultry. Main supplier Grampian has publicly stated its withdrawal of growth promoters. However, Schering-Plough, maker of a poultry vaccine called Paracox-5, can show that anti growth promoters still exist in the poultry food chain because some of the chemicals used to fight poultry disease also have a growth promoter effect. The only way to take anti growth promoters out of the food chain is to vaccinate poultry rather than use antibiotics. Naturally, Schering-Plough has an interest in the use of vaccine to replace the use of chemicals since Paracox-5 is a natural remedy with no chemicals and thus vaccinated birds are totally free of any form of growth promoter agent. Jeremy Johnson Director Animal products division, Schering-Plough {{LETTERS }}