Poult Sci. 2017 Jun 1;96(6):1696-1706. doi: 10.3382/ps/pew429.
To optimize the use of corn grain in diets for laying hens, differences in amino acid (AA) digestibility and metabolizable energy among different corn samples should be considered in feed formulation. The present study investigated the variability of AA digestibility and AMEn concentration of 20 corn samples in cecectomized laying hens. Corn grains were characterized based on their physical properties (thousand seed weight, test weight, grain density, and extract viscoelasticity), chemical composition (proximate nutrients, AA, minerals, and inositol phosphates), gross energy concentration, and in vitro solubility of nitrogen to study any relationship with AA digestibility or AMEn. The animal study comprised 4 Latin squares (6 × 6) distributed between 2 subsequent runs. Cecectomized LSL-Classic hens were individually housed in metabolism cages and fed either a basal diet containing 500 g/kg cornstarch or one of 20 corn diets, each replacing the cornstarch with one corn batch, for 8 days. During the last 4 d, feed intake was recorded and excreta were collected quantitatively. A linear regression approach was used to calculate AA digestibility of the corn. The digestibility of all AA differed significantly between the 20 corn batches, including Lys (digestibility range 64 to 85%), Met (86 to 94%), Thr (72 to 89%), and Trp (21 to 88%). The AMEn of the corn batches ranged between 15.7 and 17.1 MJ/kg DM. However, consistent correlations between AA digestibility or AMEn and the physical and chemical characteristics of the grains were not detected. Equations to predict AA digestibility or AMEn based on the grain's physical and chemical characteristics were calculated by multiple linear regressions. The explanatory power (adjusted R2;) of prediction equations was below 0.6 for the majority of AA and AMEn, and, thus, was not sufficiently precise for practical use. Possible explanations for the variation in AA digestibility and AMEn beyond the determined characteristics are discussed. In conclusion, AA digestibility and AMEn of corn grain is high in laying hens, but varies among different corn samples, with physical and chemical characteristics not suitable for explaining these variations.
为了优化蛋鸡饲料中玉米谷物的使用，在饲料配方中应考虑不同玉米样品之间氨基酸（AA）消化率和可代谢能的差异。本研究调查了 20 个玉米样品在去盲肠产蛋鸡中的 AA 消化率和代谢能浓度的可变性。根据物理特性（千粒重、测试重量、谷物密度和提取物粘弹性）、化学组成（近似营养素、AA、矿物质和肌醇磷酸盐）、总能浓度以及氮的体外溶解度对玉米进行了表征，以研究与 AA 消化率或 AMEn 的任何关系。动物研究包括 4 个拉丁方（6×6），分布在 2 个后续运行之间。单独将去盲肠的 LSL-Class 母鸡饲养在代谢笼中，用含有 500 g/kg 玉米淀粉的基础日粮或 20 种玉米日粮中的一种饲养 8 天，每一种日粮用一批玉米替代玉米淀粉。在最后 4 天，记录饲料摄入量并定量收集排泄物。采用线性回归方法计算玉米的 AA 消化率。20 批玉米之间的所有 AA 消化率均有显著差异，包括 Lys（消化率范围为 64%至 85%）、Met（86%至 94%）、Thr（72%至 89%）和 Trp（21%至 88%）。玉米批之间的 AMEn 范围在 15.7 至 17.1 MJ/kg DM 之间。然而，未检测到 AA 消化率或 AMEn 与谷物物理和化学特性之间的一致相关性。通过多元线性回归计算了基于谷物物理和化学特性预测 AA 消化率或 AMEn 的方程。对于大多数 AA 和 AMEn，预测方程的解释能力（调整后的 R2；）低于 0.6，因此对于实际使用来说不够精确。讨论了除了确定的特性之外，AA 消化率和 AMEn 变化的可能原因。总之，蛋鸡对玉米谷物的 AA 消化率和 AMEn 很高，但在不同的玉米样品之间存在差异，物理和化学特性不适合解释这些差异。
