Two experiments were carried out to evaluate the use of two methionine sources (powder or liquid) in diets based on total and digestible amino acids for white and brown growing pullets at starter phase (1 to 6 weeks old) and grower phase (11 to 16 weeks old). In each experiment, 384 birds were distributed to a completely randomized design in a 2 × 2 × 2 factorial arrangement, composed of bird strain (Hy-Line W36 and Hy-Line Brown), source of methionine (HMTBA - 88% and DL-methionine - 99%) and criteria for diet formulation (total and digestible amino acids), totaling eight diets, each with six replications of eight birds each. The characteristics evaluated were: Feed intake and intakes of crude protein and metabolizable energy; body weight and average daily gain and feed conversion ratio of the birds. There was no interaction among the factors for any of the traits. Brown pullets strain showed higher feed intake, body weight and average daily gain. Methionine sources and the criteria for diet formulation did not influence the performance characteristics. Hy-Line W36 and Hy-Line Brown pullets showed different body development profile. Powder methionine (DL-methionine - 99%) or liquid (HMTBA - 88%) as well as the criteria for diet formulation (total or digestible amino acids) provide similar performance for growing pullets.
diet formulation criteria; grower phase; ingredient; poultry; starter phase
