Valine is the fourth limiting amino acid (AA) in corn–soybean meal–based diets for broilers, and any deficiency of this AA in the diet would result in impaired growth performance. As feed-grade Val became commercially available, the focus is now on satisfying the needs of this AA in broiler diets. The purpose of this study was, therefore, to estimate the minimum requirement of digestible Val in ratio to Lys in practical diets of female Cobb-500 broilers during the starter phase (8–21 D). A dose-response experiment was conducted using 540 female broilers in a completely randomized design. A corn–soybean meal diet was formulated to be deficient only in Val, and crystalline L-glutamic acid in the basal diet was gradually replaced by L-Val, creating 6 different ratios of digestible Val to Lys. The feed intake, BW gain, feed conversion ratio, carcass parameters, bone parameters, and nitrogen excretion were evaluated. The results of this study showed that BW gain and feed conversion ratio were significantly improved by increasing the dietary digestible Val-to-Lys ratio but not feed intake. The bone parameters and nitrogen excretion showed no response to different dietary digestible Val-to-Lys ratio. Within the carcass parameters, only abdominal fat differed between treatments. The minimum requirement of the digestible Val-to-Lys ratio for optimum live performance and carcass parameters was estimated using nonlinear models and quadratic regression equations. Based on the results of the present study, it is concluded that the minimum requirement of the digestible Val-to-Lys ratio for female Cobb-500 broilers is 0.78.

缬氨酸是第四个限制性氨基酸（AA）以玉米-豆粕为基础的肉鸡日粮中，如果日粮中这种氨基酸含量不足，将导致生长性能受损。随着饲料级Val的商业化，现在的重点是满足肉鸡日粮中这种AA的需求。因此，本研究的目的是估计在初生阶段（8-21天），女性Cobb-500肉鸡的实际饮食中可消化的Val与Lys的比例的最低要求。使用540只雌性肉鸡以完全随机的设计进行了剂量反应实验。玉米-豆粕日粮被配制为仅缺乏Val，基础日粮中的结晶L-谷氨酸逐渐被L-Val替代，从而形成了6种不同的可消化Val与Lys比率。饲料摄入量，体重增加，饲料转化率，car体参数，骨骼参数，评估氮排泄量。这项研究的结果表明，增加日粮中可消化的Val-Lys比可以显着提高体重和饲料转化率，但不能提高采食量。骨骼参数和氮排泄对不同饮食的可消化Val-Lys比无反应。在the体参数内，两次治疗之间仅腹部脂肪有所不同。使用非线性模型和二次回归方程估算了可消化的Val-Lys比值以达到最佳的实时性能和car体参数的最低要求。根据本研究的结果，可以得出结论，雌性Cobb-500肉鸡的可消化Val / Lys比的最低要求为0.78。这项研究的结果表明，增加日粮可消化的Val-Lys比可显着提高BW增重和饲料转化率，但不增加采食量。骨骼参数和氮排泄对不同饮食的可消化Val-Lys比无反应。在the体参数内，两次治疗之间仅腹部脂肪有所不同。使用非线性模型和二次回归方程估算了可消化的Val-Lys比值以达到最佳的实时性能和car体参数的最低要求。根据本研究的结果，可以得出结论，雌性Cobb-500肉鸡的可消化Val / Lys比的最低要求为0.78。这项研究的结果表明，增加日粮中可消化的Val-Lys比可以显着提高体重和饲料转化率，但不能提高采食量。骨骼参数和氮排泄对不同饮食的可消化Val-Lys比无反应。在the体参数内，两次治疗之间仅腹部脂肪有所不同。使用非线性模型和二次回归方程估算了可消化的Val-Lys比值以达到最佳的实时性能和car体参数的最低要求。根据本研究的结果，可以得出结论，对于雌性Cobb-500肉鸡，可消化的Val / Lys比的最低要求为0.78。骨骼参数和氮排泄对不同饮食的可消化Val-Lys比无反应。在the体参数内，两次治疗之间仅腹部脂肪有所不同。使用非线性模型和二次回归方程估算了可消化的Val-Lys比值以达到最佳的实时性能和car体参数的最低要求。根据本研究的结果，可以得出结论，对于雌性Cobb-500肉鸡，可消化的Val / Lys比的最低要求为0.78。骨骼参数和氮排泄对不同饮食的可消化Val-Lys比无反应。在the体参数内，两次治疗之间仅腹部脂肪有所不同。使用非线性模型和二次回归方程估算了最佳可食性能和L体参数的可消化Val / Lys比的最低要求。根据本研究的结果，可以得出结论，对于雌性Cobb-500肉鸡，可消化的Val / Lys比的最低要求为0.78。