Nutritional solutions to improve broiler uniformity

The evolution of the research in non-ruminant nutrition is clear and the concepts used evolved from empirical knowledge to a more physiological and metabolic approach. In this presentation, the evolution of the methodological concepts applied to establish the nutritional requirements will be presented. The supplementation technique is generally used in dose-response trials, but is difficult to maintain the same AA ratio (IAAR). An alternative technique is the diet dilution technique, which consists in sequentially diluting a summit diet with another protein-free diet, maintaining the same IAAR in all dietary levels. The requirements determined in dose-response assays are based on average individual in the population, what make difficult to choose a reference animal to estimate the population's requirements. In this case, the Reading model allows estimating the AA intake (AAI) using a population and considering small increases in AAI based on the optimum economic intake. Unlike the dose-response method, factorial method allows the partition of the requirements of AA. The typical factorial model considers the AAI as the sum of AA requirements for maintenance and protein deposition. Models that are more complex consider the AAI as the sum of the AA requirements for maintenance and deposition in the body and feathers. Due to the scarcity of information on the AA utilization efficiency for body free of feathers and feathers, studies using the stable isotopes for partitioning the use of AA in each tissue allowed to improve UNESP models. In the Goettingen approach, the requirement for maintenance and the potential for maximum protein deposition are determined by exponential models, which is used to model AA requirements and efficiency of utilization. This method also allows using the efficiencies to determine the IAAR by deletion method. The deletion method separate the effects of each AA on protein deposition to define an IAAR. This method allows studying all AA in a single trial, being more economical and faster than the dose-response trials for this purpose. Therefore, with these studies, it was possible to improve the models to estimate the nutritional requirements and introduce new methods to collaborate to better define the nutritional levels.