Sir; Anticoccidials are meant to control coccidiosis in chickens. Some, the ionophores, are manufactured by fermentation. Professor Spedding suggests that ionophores are neither antibiotics nor growth promoters in his letter (The Grocer, April 15, p21). But they are antibiotics ­ with the properties normally associated with this group of drugs. Some also possess growth-promoting properties. In fact the most commonly used ionophores in this country have been promoted as antibiotic growth promoters, but not always under the same brand name. Spedding also says that Paracox-5, a new product available in the UK since last September and developed as an effective alternative to traditional anticoccidial drug programmes in broilers has "yet to justify being a preferable alternative to anticoccidials in growing birds". However our original Paracox is used widely for breeders and layers, and is also licensed for use in growing chickens. It has been trialled extensively in these birds. All 15 EU countries have now agreed to issue marketing authorisations for Paracox-5. Marketing authorisations are only granted when authorities are satisfied they are safe and efficient. Paracox-5 has satisfied these requirements in Europe. It has the added benefit of leaving no drug residue in birds, and no withdrawal period is required. Dr Kevin Woodward Director, international regulatory affairs, Schering-Plough Animal Health UK {{LETTERS }}