Antimicrobial compounds are commonly included in poultry diets for promoting of growth and control of diseases. The European Union banned feed grade antibiotic growth promoters, due to, not only cross-resistance, but also to the risk of possible drugs multiple resistances in human pathogenic bacteria. Only two such drug-related compounds are planned to remain in use (Gill, 1999; Bach Knudsen, 2001; Schwarz et al., 2001; Shane, 2001). Feeds containing no chemical additives are increasingly used in poultry nutrition.