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 (NR_maxT, mg/BWkg^0.67), daily nitrogen maintenance requirement (NMR, mg/BWkg^0.67), 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 NR_maxT, 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.

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.

To evaluate the response of broiler breeder hens submitted to different amino acid intakes of methionine+cystine, lysine, and threonine, and to determine the coefficients for egg output and body weight for maintenance. Three studies were performed using 160 broiler breeder hens housed individually in metabolic cages. A summit diet and a nitrogen-free diet were formulated. The levels ranged from 1.79 to 7.13, 2.49 to 8.3, and 2.04 to 6.79 g/kg of methionine+cystine, lysine, and threonine, respectively. The variables measured were feed intake, amino acid intake, rate of lay, egg weight, and egg output. The broken line model was used to evaluate the responses. It was verified that higher values of the rate of lay, egg weight, and egg output were observed for the higher concentrations of amino acids studied. A significant difference was observed for the variables rate of lay, egg weight, egg output, and body weight (p < 0.05) for the three amino acids evaluated. The amount of each amino acid required to produce one gram per egg was estimated at 12.4 mg, 14.5 mg, and 11.2 mg for methionine+cystine, lysine, and threonine, respectively. The values estimated by coefficient b that represent the amino acid for maintenance requirement were methionine+cystine, lysine, and threonine of 30.2, 32.2, and 42.4 mg/kg BW, respectively. The coefficients may be used to design additional models to study requirements nutrition in broiler breeders, allowing a better understanding of how these birds respond to different dietary amino acids.

This study aimed to assess the nutritional value of whole corn germ (WCG) in the diet of chickens. Amino acid digestibility, fatty acid digestibility, and metabolizable energy were evaluated. A metabolism assay was conducted using the precise feeding method on roosters. A completely randomized design was used, with two treatments and ten replications per rooster in each experimental unit. The treatments were as follows: WCG1, precise feeding with WCG; and WCG2, fasting birds to determine metabolic and endogenous losses in energy and fat. The variables analyzed were coefficients for amino acids in corn germ meal and fatty acid digestibility. The results showed that the standardized digestibility coefficients for amino acids in corn germ meal were (in g/kg) as follows: Lys, 920; Thr, 780; Met + Cys, 800; Arg, 910; His, 890; Ile, 950; Leu, 970; Phe + Tyr, 870; Val, 980; Gly + Ser, 740; Ala, 960; Asp, 870; and Glu, 930. The average fatty acid digestibility and AMEn were 850 g/kg and 4934 kcal/kg, respectively. Corn germ meal, which showed high digestibility of nutrients and energy, is considered an interesting ingredient for diets requiring high energy concentration.