Nutrient requirements of broilers for optimum growth and lean mass

To take advantage from genetic improvement of broiler chickens, updates must be made of the nutritional levels that promote maximum protein accretion and minimum fat deposition. The development of growth models is a valuable tool to understand nutrient deposition in poultry. This article presents experimental results and methodologies used to obtain prediction equations for true digestible lysine requirements, based on performance; however, higher dietary lysine levels are needed to minimize abdominal fat deposition. Feed conversion ratio is the most commonly used parameter to determine broiler nutritional requirements. Methionine + cystine and threonine requirements determined by feed conversion ratio optimize carcass parameters. The reduction of protein level in broiler diets does not affect performance or breast fillet yield, but linearly increases abdominal fat deposition. Further studies need to be carried out aiming at reducing the variation of the parameters used to evaluate broiler carcasses.