The present research was conducted to estimate the dietary lysine (Lys) requirement of growing female quail base on performance and carcass constitutes at 24 to 42 d of age. A dose-response diet mainly based on corn, corn gluten and soybean meal was used. Lys content was minimized in dose-response diet (10 g/kg) while assuring the minimum levels of all other essential amino acids in a manner that would meet or exceed recommendation. This experiment was carried out in a complete randomized design arrangement with 6 dietary Lys level; 10.0, 11.5, 13.0, 14.5, 16.0 and 17.5 g/kg, from 21 to 42 d of age. Each treatment was consisted of 5 floor pens as replicate with 50 quail chicks. As a result of this study increasing dietary Lys level, body weight, body weight gain and feed conversion ratio improved significantly (P<0.05). Feed intake, carcass weight, breast weight and yield, and thigh weight were significantly (P<0.05) affected by dietary Lys. The thigh yield at 42 d of age were not influenced significantly (P>0.05) by dietary Lys. Our results suggested that Lys requirement is 13.5 and 14.7 g/kg when feed conversion, body weight (BW) gain are considered and is at least 13.6 and 15.0 g/kg when and breast and thigh meat properties are taken into account in female Japanese quails at 21-42 d of age for second order polynomial and quadratic broken-line models respectively. These results indicated that the Lys requirement of 13.0 g/kg (total basis) is not adequate from 21 to 42 d of age for female Japanese quails. Future research, however, should determine lysine needs for immune system functions of quails reared in conventional environments or during an infectious challenge. KEY WORDS lysine, performance, quail, requirement.
