The description of the genetic potential is the first step to estimating amino acid requirements and the ideal amino acid relation (IAAR). The aim of this study was to estimate the parameters that describe the daily maximum theoretical nitrogen retention (NRmaxT, mg/BWkg0.67), daily nitrogen maintenance requirement (NMR, mg/BWkg0.67), protein quality (b), dietary efficiency of the limiting amino acid (bc−1) and determine the lysine requirement and the IAAR for Japanese quail breeders. Two nitrogen balance assays were performed, one assay using 49 quails distributed in seven treatments (protein levels between 70.1 and 350.3 g/kg) and seven replicates and other assay to determine the IAAR by the use of bc−1, 12 treatments and 10 replicate, with a control diet (CD) and 11 treatments that had limited essential amino acids by providing only 60% of the CD. The values obtained for NRmaxT, NMR, b and bc−1 were 3386.61, 0.000486 and 0.000101, respectively. The daily intake of Lys was 291 mg/bird day. Lys was set at 100% for determining the IAAR: 87, 67, 21, 117, 96, 66, 142, 39, and 133 for Met + Cys, Thr, Trp, Arg, Val, Ile, Leu, His, and Phr + Tyr, respectively, for Japanese quail breeders.

Background Understanding how Japanese quails respond to arginine intake has been an objective that previous studies have not fulfilled. The main responses to be quantified include the arginine requirement for maintenance (mg/kg0.67) and egg mass production (mg/g). Quantifying maintenance and production relationships are essential steps for predicting animal response. The current study aimed to describe how quails respond to arginine intake and determine arginine requirements for maintenance and egg production in Japanese quails. Methods The experiment was carried out in a completely randomized design, with seven treatments and seven replicates with individual birds as experimental units. The arginine levels were: 2.43, 3.64, 4.85, 6.07, 9.07, 12.13, and 14.56 g/kg. The experiment lasted for eight weeks. The variables analyzed were daily arginine intake, daily arginine deposition in eggs, and body weight. The data were analyzed using a mixed model, with the experimental unit being the random effect and the experimental levels of arginine as a fixed effect. When the effect of arginine levels was detected (P ≤ 0.05), saturation kinetics and an exponential model with four parameters (monomolecular) were adopted. ANOVA results indicated that dietary arginine levels significantly affected (P < 0.01) the analyzed variables. The formulation strategy of the experimental diets allowed amplitude in the dietary arginine levels, and according to bird responses, arginine was the limiting nutrient. Results The arginine requirement for body weight maintenance (BW0.67) was estimated to be 90 mg/kg BW0.67 by the monomolecular function. The requirement for egg mass (EM) production was estimated to be 25 mg/g per egg. A factorial model was parameterized as follows: daily arginine intake mg/bird = 90 × BW0.67 + 25 × EM ± 12 mg. The model was applied to data obtained from literature, and the resultant error was within the expected limit of 12 mg. The recommended daily arginine intake for the daily production of 11 g of egg and 180 g of BW was determined to be 304 mg/bird. The current study provides procedures that researchers can easily adopt.

The objective of this study was to determine the ideal amino acid ratio for Japanese quail based on egg quality. In total, 120 Japanese quail were used. A completely randomized design was used with 12 treatments and 10 replicates per treatment. The treatments consisted of a balanced protein (BP) and the subsequent 11 diets were obtained by the 40% deletion of the BP a specific test for Lys, Met + Cys, Thr, Trp, Arg, Gly + Ser, Val, Ile, Leu, His, and Phr + Tyr. The trial lasted for 25 days. At the end of the trial, egg weight (EW), albumen height, albumen diameter, albumen index, yolk height, yolk diameter, yolk index, Haugh unit, eggshell weight (ESW), and eggshell percentage were measured. The ideal ratio was calculated when a statistical difference was detected using Dunnett’s test. Only the EW and ESW variables differed from those of BP. The ideal amino acid ratios considering Lys as 100 for EW and ESW were Met + Cys 82 and 83, Thr 60 and 68, Trp 18 and 21, Arg 109 and 112, Gly + Ser 99 and 102, Val 77 and 87, Ile 61 and 67, Leu 155 and 141, His 34 and 37, Phe + Try 134 and 133, respectively.

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