Modeling the response of Japanese quail hens to lysine intake

Studies on Japanese quails have been conducted using the dose response method over the years and, to date, there have been few studies on the response of quails to the amino acid intake, such as lysine. Thus, the objectives of this study were to: (1) determine an optimal adaptation period for Lys requirement studies with quails, (2) estimate the maintenance requirements for Lys, (3) determine the efficiency of Lys utilization, and (4) determine the requirements for egg output of quails. The studies were conducted in a complete random design, with 7 concentrations of Lysine (Lys) (2.6 to 13.0 g/kg) and 7 replicates with 7 quails per cage. The eighth concentration was included to confirm that Lys was actually the first limiting amino acid in the dietary protein. The experiment began at 14 weeks of age, quail with peak egg production, and finished after 10 weeks of data collection. The variables analyzed were feed intake (FI), Lys intake, body weight (BW), egg production (EP), egg weight (EW), weight gain, and egg output (EO, g/g). The results showed that 3 weeks of adaptation and 4 weeks of data collection period were enough for the quail to adapt and stabilize their responses to experimental diets. The responses of quails to Lys intake were evaluated using broken line analysis, and Lys requirements for maintenance and EO were estimated using monomolecular function The Lys requirements for maintenance and egg output were estimated to be 156 mg/BWkg0.75 per day and 21 mg/g of egg, respectively. These results were used to develop the following approach factorial: Lys = 21EO + 156BW(0.75). The current study provides procedures (determine an optimal adaptation period for amino acid studies with quails) and methods (utilization of dilution technique to determine Lys maintenance requirements and utilization efficiency) designed for quails as well as a simple and flexible model that can be quickly adopted by researchers. Future studies should improve the coefficients (mg of Lys required for EO and BW) proposed in this research, especially to maintenance requirements.