Relationship of methionine plus cystine with lysine in diets for laying Japanese quails

The objective of this work was to evaluate the relationships of methionine plus cystine with lysine for Japanese quails in the laying phase. Thus, it was used 480 birds at initial age of 65 days, distributed in randomized block design with 6 treatments, 10 replicates and 8 birds per experimental unit. The treatments consisted of basal diet deficient in methionine plus cystine (0.65%), with 19.6% of crude protein and 2800 kcal of metabolizable energy/kg of ration, supplemented with six levels of DL-methionine 98% (0.116; 0.167; 0.218; 0.269; 0.320 and 0.371%), corresponding to methionine plus cystine with lysine ratio of 0.65, 0.70, 0.75, 0.80, 0.85 and 0.90, and the digestible lysine set at a suboptimal level of 1.00. The parameters studied were: feed intake, egg production per hen day, egg production per housed hen, commercial egg production, egg weight, egg mass, feed conversion per egg mass, feed conversion per dozen eggs, viability of birds, weight of the egg components (yolk, albumen and shell), percentage of components of eggs, diameter and height of the eggs and specific gravity. It was observed an increasing linear effect for feed intake, egg diameter, shell weight and percentage of yolk. For eggshell percentage, it was observed a decreasing linear effect. For the weight of the eggs, the best adjustment was obtained by using the Linear Response Plateau model. A quadratic effect was observed for egg mass, feed conversion per egg mass, egg production per hen day, egg production per housed hen, yolk weight, albumen weight and height of the eggs. The relationship of methionine plus cystine with lysine of 0.84 which corresponds to the consumption of 221.0 mg/bird/day of methionine + cystine provides better performance and satisfactory quality of Japanese quail eggs