Mehri M, Bagherzadeh-Kasmani F, Rokouei M
Department of Animal Science,College of Agriculture,University of Zabol,Zabol,98661-5538,Iran.
Animal. 2016 Mar;10(3):390-5. doi: 10.1017/S1751731115002128. Epub 2015 Oct 26.
The first three essential amino acids (EAA) for broilers including methionine (Met), lysine (Lys) and threonine (Thr) may greatly influence the growth of chick muscles at early stages of life. In order to survey the potential effects of those EAA on growth muscles, a rotatable three-variable central composite design (CCD) was conducted to track the interrelationships of dietary digestible Met (dMet), Lys (dLys) and Thr (dThr) for optimization of processing yields in broiler chicks using response surface methodology. A total of 60 floor pens of six birds each were assigned to 15 dietary treatments based on CCD containing five levels of dMet (0.416% to 0.584% of diet), dLys (0.881% to 1.319% of diet) and dThr (0.532% to 0.868% of diet) from 3 to 16 days of age. Experimental treatments significantly affected breast mass (BM) and leg mass (LM) of the birds (P<0.05) in which the main effect of dLys on BM was threefold higher than the main effect of dThr, and interaction effect between dMet and dLys was observed on BM (P<0.05). However, in the case of LM, the main effect of dThr was higher than the main effects of dMet and dLys and highest interaction effect exist between dThr and dMet (P<0.05). The second-order models for BM and LM were fitted by least squares regression. Canonical analysis revealed that the stationary points for carcass components were saddle points, thus ridge analysis was performed for getting optimal values of each EAA. Ridge analyses of BM and LM models showed that the maximum BM point may be obtained with 0.58%, 1.05% and 0.76% of dMet, dLys and dThr, respectively, in diet, and maximum LM point may be achieved with 0.58%, 1.09% and 0.70% of dMet, dLys and dThr, respectively, in diet. The resultant ideal ratios of dMet and dThr to dLys were 55% and 72% for BM; 53% and 64% for LM. Moreover, sensitivity analysis showed that the most important amino acids in BM and LM models were Lys and Thr, respectively. In conclusion, providing these three amino acid for BM optimization may warrant LM optimization and higher ideal ratios of dMet and dThr for breast muscle may indicate the higher importance of these EAA in this muscle than those in thigh muscle.
肉鸡的前三种必需氨基酸（EAA），即蛋氨酸（Met）、赖氨酸（Lys）和苏氨酸（Thr），可能会在雏鸡生命早期极大地影响其肌肉生长。为了研究这些必需氨基酸对生长肌肉的潜在影响，采用了旋转三变量中心复合设计（CCD），运用响应面法追踪日粮中可消化蛋氨酸（dMet）、赖氨酸（dLys）和苏氨酸（dThr）之间的相互关系，以优化肉鸡的生产性能。从3日龄到16日龄，根据包含五个dMet水平（占日粮的0.416%至0.584%）、dLys水平（占日粮的0.881%至1.319%）和dThr水平（占日粮的0.532%至0.868%）的CCD，将总共60个地面围栏，每个围栏6只鸡，分配到15种日粮处理中。实验处理显著影响了鸡的胸肌质量（BM）和腿肌质量（LM）（P<0.05），其中dLys对BM的主要影响比dThr的主要影响高三倍，并且观察到dMet和dLys之间对BM存在交互作用（P<0.05）。然而，对于LM而言，dThr的主要影响高于dMet和dLys的主要影响，并且dThr和dMet之间存在最高的交互作用（P<0.05）。通过最小二乘法回归拟合了BM和LM的二阶模型。典型分析表明，胴体组成部分的驻点是鞍点，因此进行了岭分析以获得每种必需氨基酸的最佳值。BM和LM模型的岭分析表明，日粮中dMet、dLys和dThr分别为0.58%、1.05%和0.76%时，可能获得最大BM点；日粮中dMet、dLys和dThr分别为0.58%、1.09%和0.70%时，可能实现最大LM点。BM中dMet和dThr与dLys的理想比例分别为55%和72%；LM中分别为53%和64%。此外，敏感性分析表明，BM和LM模型中最重要的氨基酸分别是Lys和Thr。总之，为优化BM提供这三种氨基酸可能保证LM的优化，并且胸肌中dMet和dThr的较高理想比例可能表明这些必需氨基酸在该肌肉中比在大腿肌肉中更重要。
