An experiment was carried out to estimate the optimum level of digestible threonine for white-egg and brown-egg laying hens in the second laying cycle. It was used 360 laying hens, 180 were white-egg and 180 were brown-egg laying hens which were distributed in a complete randomized design in 5 x 2 factorial arrangement (5 levels threonine x 2 lines of laying hens). The levels of digestible threonine used were the following: 0.380, 0.413, 0.445, 0.478 and 0.511%. It was evaluated performance data (production, egg weight and mass), egg components (albumen, yolk and shell), egg internal quality (Haugh units, albumen and yolk indexes) and percentage of non-commercial eggs and body weight parameters. Through the obtained results, it was estimated for white-egg laying hens, levels of digestible threonine of 0.446%, which matches a daily intake of 487 mg/hens and a lysine: threonine relationship equal to 68; for brown-egg laying hens, the estimate level of digestible threonine was 0.465% with a daily intake of 505 mg/hens and a lysine: threonine relationship of 71. By comparing the relationship mg digestible threonine per gram of produced eggs, values of 9.5 and 10.0 mg threonine/gram egg are estimate; gram of produced egg.
amino acid relationship; egg production; performance
