Requirement of digestible methionine + cystine for growing Japanese quail and its subsequent effects on laying phase

- The objective of this study was to estimate the nutritional requirement of digestible methionine + cystine for Japanese quail during the growth phase and its residual effect on the laying phase. One experiment was conducted, including three phases: starter, from 1 to 14 days of age; grower, from 15 to 42 days of age; and laying, from 43 to 168 days of age. The experimental design was entirely randomized with five treatments (0.52, 0.64, 0.76, 0.88, and 1.00% of digestible methionine + cystine) and five replicates. In starter phase, 48 quail/experimental unit (box) were used; in grower phase, 31 quail/experimental unit (box) were used, which were reared until 14 days old, receiving conventional feed and, in laying phase, 12 quail/experimental unit were selected from grower phase to evaluate the residual effect. To evaluate animal performance, feed intake (g/bird), body weight (g), weight gain (g), feed conversion (g/g), and viability (%) were analyzed. At 14 and 42 days of age, the relative weight (%) of liver, spleen, and cloacal pouch organs, the birds’ warping (%) and body chemical composition (%) were evaluated. During laying, performance and egg quality were evaluated. In the starter and grower stages, quadratic effects were observed for all performance variables. Laying performance results confirmed the estimates obtained in the grower phase; however, there was no effect on egg quality. Considering the best feed conversion, the nutritional recommendation of digestible methionine + cystine for Japanese quail in the starter phase is 0.85% and in the grower phase, it is 0.77%, corresponding to daily intake of 50.43 and 158.5 mg of digestible methionine + cystine/day, respectively