Department of Animal Science, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.
Department of Animal Nutrition, Institute of Agrifood Research and Technology, Centre Mas Bové, Reus 43280, Spain.
Poult Sci. 2020 Sep;99(9):4496-4504. doi: 10.1016/j.psj.2020.06.013. Epub 2020 Jun 25.
This experiment was conducted to evaluate the chemical composition and standardized ileal amino acid digestibility of corn grain and to use these data to develop prediction equations for estimating total amino acids (TAAs) and standardized ileal digestible amino acids (SIDAAs) for broiler chickens. Four types of corn grains were obtained from different origins (Brazil, Ukraine, Russia, and Iran). Eighty-day-old Ross 308 male broiler chicks were fed a standard diet until day 18, and experimental diets were fed from 19 to 24 D of age. Five dietary treatments consisted of 4 semi-purified diets containing corn from each origin as the only source of amino acid (AA) and a N-free diet for determination of basal endogenous AA losses. Assay diets contained 939 g of test corn/kg. The concentration of crude protein and gross energy ranged from 7.58 to 8.39% (coefficient of variation [CV] = 4.72%) and 4,121 to 4,621 kcal/kg (CV = 5.09%), respectively. There was significant variation among the 4 corn grains in standardized ileal digestibility (SID) for CP, Phe, Leu, Asp, Glu, Ser, Gly, Ala, and Tyr (P ≤ 0.05). The results of linear regression showed that linear prediction equations based on protein content can be used to predict the TAA and SIDAA contents (e.g., TLys = 0.041 × CP, adj R = 95.9, standard error of prediction [SEP] = 0.05; SIDLys = 0.0356 × CP, adj R = 96, SEP = 0.051). Inclusion of other proximate components of test samples into the regression equation increased the R value and decreased the SEP value (e.g., TLys = 0.329 × crude fiber [CF] ‒ 0.209 × Ash, adj R = 99.9, SEP = 0.005; SIDLys = ‒1.1591 + 0.836 × CF ‒ 0.055 × Ash, adj R = 99.9, SEP = 0.001). The concentration of TAA and SIDAA was highly correlated (adj R > 89%) for most AA and showed that the amount of SIDAA could be predicted from its total concentration with a high degree of accuracy (e.g., SIDLys = 0.0023 + 0.861 × TLys, adj R = 99.9, SEP = 0.0001). In conclusion, this in vitro assays and equations accurately predicted TAA and SIDAA corn grain samples for broiler chickens and can serve as a reference analysis to develop calibration equations for rapid feed quality evaluation methods such as near-infrared reflectance spectroscopy.
本试验旨在评估玉米的化学成分和标准回肠可消化氨基酸含量，并利用这些数据为肉鸡开发总氨基酸（TAA）和标准回肠可消化氨基酸（SIDAA）的预测方程。从不同来源（巴西、乌克兰、俄罗斯和伊朗）获得了四种玉米。80 日龄 Ross 308 雄性肉鸡在标准日粮中饲养至 18 日龄，19 日龄至 24 日龄龄饲喂试验日粮。五种处理日粮由 4 种半纯化日粮组成，每种日粮均以一种来源的玉米作为唯一的氨基酸（AA）来源，无氮日粮用于测定基础内源 AA 损失。测定日粮含 939g/kg 试验玉米。粗蛋白和总能的浓度范围为 7.58%至 8.39%（变异系数 [CV] = 4.72%）和 4121 至 4621kcal/kg（CV = 5.09%）。四种玉米的标准回肠可消化率（SID）存在显著差异（CP、Phe、Leu、Asp、Glu、Ser、Gly、Ala 和 Tyr，P≤0.05）。线性回归结果表明，基于蛋白质含量的线性预测方程可用于预测 TAA 和 SIDAA 含量（例如，TLys=0.041×CP，调整 R = 95.9，预测标准误差 [SEP] = 0.05；SIDLys=0.0356×CP，调整 R = 96，SEP=0.051）。将测试样品的其他近似成分纳入回归方程会增加 R 值并降低 SEP 值（例如，TLys=0.329×粗纤维 [CF] -0.209×灰分，调整 R = 99.9，SEP = 0.005；SIDLys=-1.1591+0.836×CF-0.055×灰分，调整 R = 99.9，SEP=0.001）。大多数 AA 的 TAA 和 SIDAA 浓度高度相关（调整 R >89%），表明 SIDAA 的量可以通过其总浓度以高精度预测（例如，SIDLys=0.0023+0.861×TLys，调整 R = 99.9，SEP=0.0001）。总之，本体外测定和方程准确预测了肉鸡玉米的 TAA 和 SIDAA，可作为开发近红外反射光谱等快速饲料质量评价方法校准方程的参考分析。
