National audience ; When compared to animals of the dual purpose type in the same breed, Belgian Blue double muscled bulls exhibit, at least, similar average daily gain with lower feed intake. The higher feed efficiency in the double muscled type is mainly explained by the composition of the weight gains, the muscle content is minimum 60 kg higher and the fat content 30 kg lower than in the dual pur pose type when slaughtered at a similar live weight. In both types, the dressing percentage and the lean meat proportion in the carcass increase with final liveweight. The chemical composition and the sensory characteristics of meat are also influenced by double muscling. The fat content is reduced and the polyunsaturated fatty acids proportion is increased in the double muscled type, resulting in a nutritional advantage. The difference in sensory characteristics could be, only partially explained by the fas ter post mortem pH drop. The paler meat is mainly related to the myoglobin content. The advantage of the double muscled type in terms of tenderness, due to a low collagen content, is not exhibited in a << choice >> cut of the carcass with a low level of collagen, Finally, according to most of the available data, the water holding capacity of meat of double muscled animals seems not very different. The concentrations of several blood metabolites indicate a partition of the absorbed nutrients propitious to protein deposition and unpropitious to fat deposition in double muscled animals. During the fattening period, this specific partition can be related to endocrine characteristics, mainly growth hormone and insulin. ; Lorsqu’on les compare à des sujets mixtes de la même race, les taurillons Blanc Bleu Belge (BBB) culards réalisent des gains quotidiens moyens au moins aussi élevés tout en consommant moins d’aliments. L’amélioration de l’efficacité alimentaire est expliquée principalement par la composition des gains de poids : la carcasse d’un sujet BBB culard contient au moins 60 kg de muscle en plus et ...