Broiler chickens have been selected for increased growth rate and adapted to consumer demands. A range of commercial products is being developed from slower growing country-type meat chickens (named ‘Label’ in France) as well as from faster growing broilers with a high yield of breast meat. Nutritionists have to satisfy a need for feeding programmes adapted to meet the demands for various end-products. Selection for growth rate has to be shown to change the food intake behaviour of chickens (i.e. Barbato et al., 1980). Emmans (1991) demonstrated that chickens are able to adjust their food choices if the paradigm permits an adequate choice. In a series of experiments (see Picard et al., 1994 for review) the authors concluded that ‘high producing animals are not necessarily those that will react most clearly to an amino acid deficiency by altering their food intake and/or their feeding behavior’.