Ospina-Rojas I C, Murakami A E, Duarte C R A, Nascimento G R, Garcia E R M, Sakamoto M I, Nunes R V
Department of Animal Science, Universidade Estadual de Maringá; Av. Colombo, 5790, Bloco J45, 87020-900, Maringá, PR, Brazil.
Department of Animal Science, Universidade Estadual de Mato Grosso do Sul; Rodovia Aquidauana, km 12, 79200-000, Aquidauana, MS, Brazil.
Poult Sci. 2017 Apr 1;96(4):914-922. doi: 10.3382/ps/pew319.
The objective of this study was to determine the requirements and interactions between the standardized ileal digestible (SID) Leu and Val levels in low-protein diets, and their effects on performance, serum characteristics, carcass yield and diameter of muscle fibers of broiler chickens from d 21 to 42 posthatch. A total of 1,500 21-day-old Cobb 500 male broiler chickens were distributed in a completely randomized design in a 5 × 5 factorial arrangement for a total of 25 treatments with 3 replicates of 20 birds each. Treatments consisted of 5 SID Leu levels (1.0, 1.2, 1.4, 1.6, or 1.8%) and 5 SID Val levels (0.52, 0.67, 0.82, 0.97, or 1.12%). At 42 d of age, there was interaction (P < 0.05) between the SID levels of Leu and Val on feed intake and weight gain. There was a quadratic effect (P < 0.05) of Leu and Val levels on feed conversion, with minimal point estimated at the levels of 1.19 and 0.86%, respectively. Dietary Leu supplementation reduced linearly (P < 0.05) serum concentrations of triglycerides and β-hydroxybutyrate. Dietary Leu increased (P ≤ 0.05) the fiber diameters of the pectoralis major muscle and breast yield at the levels of 1.24 and 1.13%, respectively, while the thigh yield was improved with the level of 0.71% Val. Abdominal fat decreased linearly (P < 0.05) with increasing levels of dietary Leu and Val. The SID Leu and Val levels needed to optimize weight gain and feed conversion in low-CP diets for broiler chickens from d 21 to 42 posthatch were estimated at 1.15 and 0.86%, and 1.19 and 0.86%, respectively. The supplementation of Leu and Val can reduce the abdominal fat deposition in birds fed low-CP diets during the grower phase. Leu and Val interactions can influence the performance but not the serum characteristics, carcass yield and diameter of muscle fibers of broilers fed low-protein diets. Therefore, it is necessary to consider the dietary Leu content to estimate the ideal level of Val in low-CP diets for optimum broiler performance.
本研究的目的是确定低蛋白日粮中标准化回肠可消化（SID）亮氨酸和缬氨酸水平之间的需求及相互作用，以及它们对孵化后21至42日龄肉鸡的生产性能、血清特性、胴体产量和肌纤维直径的影响。总共1500只21日龄的科宝500雄性肉鸡采用完全随机设计，按5×5析因排列，共25个处理，每个处理20只鸡，重复3次。处理包括5个SID亮氨酸水平（1.0%、1.2%、1.4%、1.6%或1.8%）和5个SID缬氨酸水平（0.52%、0.67%、0.82%、0.97%或1.12%）。在42日龄时，亮氨酸和缬氨酸的SID水平在采食量和体重增加方面存在交互作用（P<0.05）。亮氨酸和缬氨酸水平对饲料转化率有二次效应（P<0.05），最低点分别估计为1.19%和0.86%。日粮中添加亮氨酸可使甘油三酯和β-羟基丁酸的血清浓度呈线性降低（P<0.05）。日粮亮氨酸分别在1.24%和1.13%水平时可使胸大肌纤维直径增加（P≤0.05）和胸肌产量提高，而缬氨酸水平为0.71%时可提高腿肌产量。随着日粮亮氨酸和缬氨酸水平的增加，腹脂呈线性下降（P<0.05）。估计孵化后21至42日龄肉鸡低粗蛋白日粮中优化体重增加和饲料转化率所需的SID亮氨酸和缬氨酸水平分别为1.15%和0.86%，以及1.19%和0.86%。在生长阶段，添加亮氨酸和缬氨酸可减少低粗蛋白日粮喂养鸡的腹脂沉积。亮氨酸和缬氨酸的相互作用会影响低蛋白日粮喂养肉鸡的生产性能，但不影响其血清特性、胴体产量和肌纤维直径。因此，在估计低粗蛋白日粮中缬氨酸的理想水平以实现最佳肉鸡生产性能时，有必要考虑日粮亮氨酸含量。
