The objective of this research was to determine the coefficients of responses to egg mass and body weight to intake of isoleucine, valine and tryptophan by Reading Model and simulate the economic optimum level for different production scenarios. Will be used 192 broiler Cobb ® with 48 weeks of age, 64 birds from each trial. Will be used eight treatments and eight replicates of one bird each. The treatments consist of seven levels of the respective amino acid being tested. The eighth amino acid of each treatment, consist level against test. Each test will run for nine weeks, with the first five adaptation and the last four data collection. The data of ingestion of the amino acid, mass production, egg weight, standard deviation, egg mass weight and will be subjected to regression analysis to estimate the model parameters of Reading. The other variables of performance and body composition will be treated deterministically using the linear plateau and / or quadratic polynomial. For the tests will be used for maintenance of 126 roosters bloodline cutting Cobb ®, 42 animals for each amino acid. The treatments consist of six levels of increasing their amino acid testing (tryptophan, isoleucine and valine). The seventh processing of each amino acid, consist level against test. The trial period is 120 hours, with the first 48 hours the period for emptying of the gastrointestinal tract and 72 hours later, the birds will be fed the experimental diets by gavage. The requirement for maintenance each amino acid is obtained by linear regression of nitrogen balance (NB) according to the intake of each amino acid, being defined as the amount of amino acid required to maintain BN zero. Statistical analyzes will be performed in SAS version 9.2 computer program.
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