Twenty-seven week-old commercial laying hens were allotted to a completely randomized design with a 3x3 factorial arrangement with three replicates of six birds per treatment. The factors consisted of hree methods for estimatingamino acid ingredient composition (Brazilian tables, prediction equations and factor for correcting amino acid in function of ingredient protein level) and three amino acid recommendations, being two for digestible amino acids and one for total amino acid. Methods for estimation amino acid ingredients composition had effect only on feed conversion and shell thickness. The better results were found by using Brazilian tables for calculating amino acid values of ingredients used in diet formulation. Although, amino acid recommendations affected all performance parameters, they did not affect egg quality. Bird performance was prejudiced by digestible amino acid recommendation. The two digestible amino acid recommendations led to similar performances, which were lower than those reached after following total amino acid recommendation. The worst performance observed in birds fed diets balanced according to digestible amino acid recommendations might be a consequence of nitrogen lacking for synthesis of non essential amino acids, once protein level was reduced (12.5% CP), and also explained by the deficiency in arginine, histidine, isoleucine, leucine and valine because their requirements were not considered in the diet formulation.
digestible amino acids; low protein; prediction equations; production cost; total amino acids
