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 R2 = 95.9, standard error of prediction [SEP] = 0.05; SIDLys = 0.0356 × CP, adj R2 = 96, SEP = 0.051). Inclusion of other proximate components of test samples into the regression equation increased the R2 value and decreased the SEP value (e.g., TLys = 0.329 × crude fiber [CF] ‒ 0.209 × Ash, adj R2 = 99.9, SEP = 0.005; SIDLys = ‒1.1591 + 0.836 × CF ‒ 0.055 × Ash, adj R2 = 99.9, SEP = 0.001). The concentration of TAA and SIDAA was highly correlated (adj R2 > 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 R2 = 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.

中文翻译：

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肉鸡玉米籽粒化学成分与回肠标准化可消化氨基酸含量的关系。

进行该实验以评估玉米籽粒的化学组成和标准化回肠氨基酸消化率，并使用这些数据来开发预测方程，以估算肉鸡的总氨基酸（TAA）和标准化回肠可消化氨基酸（SIDAAs）。从不同的来源（巴西，乌克兰，俄罗斯和伊朗）获得了四种类型的玉米籽粒。对80日龄的Ross 308雄性肉鸡进行标准日粮饲喂直至第18天，实验日粮的饲喂年龄为19至24D。五种饮食疗法包括4种半精制饮食，其中每种来源的玉米都是唯一的氨基酸（AA）来源，而无氮饮食则用于测定基础内源性AA损失。分析饮食中含有939克测试玉米/千克。粗蛋白和总能量的浓度范围为7.58至8。分别为39％（变异系数[CV] = 4.72％）和4,121至4,621 kcal / kg（CV = 5.09％）。CP，Phe，Leu，Asp，Glu，Ser，Gly，Ala和Tyr的标准化回肠消化率（SID）在4种玉米籽粒之间存在显着差异（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，adj R2 = 95.9，预测标准误差[SEP] = 0.05； SIDLys = 0.0356×CP，调整R2 = 96，SEP = 0.051）。在回归方程中包含测试样品的其他邻近成分会增加R2值，并降低SEP值（例如TLys = 0.329×粗纤维[CF] ‒ 0.209×灰分，调节R2 = 99.9，SEP = 0.005； SIDLys = ‒ 1.1591 + 0.836×CF ‒ 0.055×灰分，调整R2 = 99.9，SEP = 0.001）。对于大多数AA，TAA和SIDAA的浓度高度相关（adj R2> 89％），表明从其总浓度可以高度准确地预测SIDAA的量（例如SIDLys = 0.0023 + 0.861×TLys，调整R2 = 99.9，SEP = 0.0001）。总之，这种体外测定和方程式可以准确地预测肉鸡的TAA和SIDAA玉米籽粒样品，并且可以作为参考分析，开发用于快速饲料质量评估方法（例如近红外反射光谱法）的校准方程式。