Estimation of lysine requirements for growing Japanese quails

This study was conducted to estimate the lysine requirements of growing meat-type Japanese quails based on different growth responses using different regression models. Experimental treatments including five doses of dietary lysine (9.40, 10.9, 12.4, 13.9 and 15.4 g/kg of diet) were used in a dose-response platform from 7 to 21 day of age. A total of 375, 7-day old quail chicks were randomly allotted to one of five dietary treatments with five replicate pens and 15 birds per pen. Performance traits including feed intake (FI), weight gain (G) and feed:gain (F:G) and carcass criteria including dressing (DRS), breast meat yield (BMY) and leg meat yield (LMY) were measured and used to fit several models (e.g., spline and quadratic polynomial models). Except FI and LMY, other parameters responded to dietary treatments (p < .05), in which G linearly but F:G, DRS and BMY quadratically responded to incremental levels of lysine (p < .05). On the basis of statistical merit, the best estimation of lysine requirements for G, F:G, BMY and DRS was 12.39 (R² : .93 and S_y.x : 2.35), 12.40 (R² : .98 and S_y.x : 0.001), 13.64 (R² : .99 and S_y.x : 0.15) and 13.80 (R² : .99 and S_y.x : 0.50) g/kg of diet respectively. This study showed that lysine requirements for maximum carcass yield and its attributes (e.g., BMY) might be higher than those needed for maximum growth rate or feed efficiency.