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Lysine Requirements in Starter-Phase Japanese Quail (Coturnix japonica) Through Dose-Response Modelling: Interactions
Hamid Valizadeh1, Mehdi Taghinejad-Roudbaneh1, Ruhollah Kianfar2
1Department of Animal Science, Faculty of Agriculture and Natural Resources, Ta.C., Islamic Azad University, Tabriz, Iran.
Background:
The diet of Japanese quail (Coturnix japonica) during the critical post-hatching period (0-14 days) provides a basis for long-term productivity, but the exact lysine requirements are not well characterized in modern high-yield strains. Precision poultry nutrition requires updated amino acid (AA) recommendations that account for interactions between dietary crude protein (CP) and lysine, the reference AA for ideal protein specification.
Objectives:
To determine optimal lysine requirements for growing Japanese quail (0-14 days) at three CP levels (22%, 24%, 26%) using a dose-response method, and to compare linear versus quadratic broken-line models for estimating lysine thresholds.
Methods:
A fully randomized factorial design used 900 Japanese quail chicks allocated to 15 dietary treatments (3 CP × 5 lysine levels: 0.95%, 1.1%, 1.25%, 1.4 %and 1.55 %). Growth performance, feed efficiency and carcass characteristics were evaluated. Lysine requirements were estimated by linear and quadratic broken-line regression using the non-linear least squares (NLIN) procedure in Statistical Analysis System (SAS) software version 9.4.
Results:
Dietary CP and lysine levels significantly (p < 0.01) affected all growth parameters. Optimal lysine (1.4%) maximized body weight (73.93 g), weight gain (66.50 g) and protein efficiency ratio (PER) (2.70). Significant interactions (p < 0.05) occurred between CP and lysine for feed intake (FI), feed conversion ratio (FCR) and PER. Lysine requirements for weight gain using the linear broken-line model were 1.20%, 1.32% and 1.4% for 22%, 24% and 26% CP, respectively, showing superior fit (R2 = 66.24%-94.45%) compared to quadratic models.
Conclusions:
Lysine requirements of Japanese quail depend on dietary CP level. The linear broken-line model is more reliable than the quadratic approach. Producers should use 1.32%-1.42% lysine in starter diets, adjusting according to CP content. Future research should confirm these requirements under commercial production conditions and explore interactions with other key AAs in reduced formulae.
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