With the objective to establish the nutritional requirement of methionine + cystine for light and semi-heavy laying hens, in the period from 34 to 50 weeks old, 360 laying hens (half Lohmann and half Lohmann Brown) were submitted to a basal ration containing 2.850 kcal ME/kg, 15.0% CP, supplemented with five levels (0.00, 0.052, 0.107, 0.162, and 0.217%) of DL-methionine, to provide 0.517, 0.569, 0.624, 0.679, and 0.734% of digestible methionine + cystine in the rations. A 5 x 2 (methionine + cystine level and laying hen strain) factorial arrangement, with six replications per treatment and six hens per experimental unit in a completely randomized design was used. Egg production (%), egg mass and average egg weight (g), feed intake (g/hen.day), feed conversion (kg feed /egg dozen), body weight change (g) and internal egg quality (Haugh Units, albumen and yolk index) were evaluated. The methionine + cystine levels did not affect the body weight change, feed intake and egg quality in both laying hen strains. Feed conversion and egg production were positive influenced by the methionine + cystine level, as well as average egg weight and egg mass that presented a quadratic effect, exception for average eggs weight of semi heavy laying hens that presented linear effect. The digestible methionine + cystine requirement, estimated by quadratic model, for the light and the semi-heavy laying hens, was 0.693 and 0.692% in the ration, corresponding to the daily intake per hen of 825 and 793 mg lysine/day, respectively.
ideal protein; layer; poultry; sulfur amino acid
