This research was carried out using 360 laying hens (180 Lohmann LSL and 180 Lohmann Brown), to establish the nutritional requirement of digestible methionine+cystine in the period from 54 to 70 weeks of age. A completely randomized experimental design, in a 5 × 2 factorial arrangement (5 levels of digestible methionine+cystine and 2 laying hen strain), with 6 replications and 6 hens per experimental unit, was used. The treatments consisted of diets supplemented with 5 levels of DL-methionine (98%), resulting in 0.492, 0.544, 0.596, 0.648 and 0.700% of digestible methionine+cystine in diets. The parameters analyzed were: egg production, egg weight, egg mass, feed intake, digestible methionine+cystine intake, feed conversion, egg components (albumen, yolk and shell), internal quality (Haugh unit, albumen index and yolk index), the percentage of eggs does not trade and the body weight gain. The levels of methionine+cystine digestibles studied influenced the egg production, egg weight, egg mass, feed intake, digestible methionine+cystine intake, feed conversion, weight yolk and shell, and the body weight gain. The requirements of digestible methionine+cistine were estimated by polynomial regression models. The digestible methionine+cystine requirement, estimated for the laying hens light-weight was of 0.645% in the ration, corresponding to daily intake per hen of 712 mg and 12.5 g of methionine+cystine digestibles/g egg mass produced. For the laying hens semi-heavy was of 0.655% in the ration, corresponding to daily intake per hen of 723 mg and 13.2 g of methionine+cystine digestibles/g egg mass produced.
amino acid; eggs; laying hens; performance
