Dietary net energy for maintenance (NEm) and gain (NEg) can be estimated using calculations based on live performance or adjusted-final body weight, which is calculated based on carcass characteristics. These values are commonly referred to as performance adjusted (pa) NEm (paNEm) and NEg (paNEg). The NEm and NEg of a diet can also be estimated by adding recovered energy (RE) with heat production (HP) derived from an automated head chamber system (AHCS), which we will term gas-adjusted (ga) NEm (gaNEm) and NEg (gaNEg). Furthermore, HP from the Brouwer’s equation requires an estimate of urine nitrogen (UN) excretion, which can be calculated based on N intake, blood urea N, UN concentration and urine creatinine, or it could be zeroed. Alternatively, HP can be calculated using an alternative equation based on the respiratory quotient. Demonstrating agreement between pa and ga derived dietary energy values provides an opportunity to validate using the AHCS for energetic experiments and this comparison has not been conducted previously. Accordingly, the objective of this experiment was to assess the agreement between live and carcass paNEm and paNEg with gaNEm and gaNEg, where HP was calculated using 4 different approaches. Estimates of HP were not different (P = 0.99) between the 4 approaches employed, indicating that all options investigated are appropriate. Live paNEm and paNEg had higher agreement [Lin’s concordance correlation coefficient (CCC) = 0.91] with gaNEm and gaNEg than carcass values (CCC ≤ 0.84). These results suggest that researchers can implement the AHCS to provide good estimates of dietary energy values in finishing beef cattle that are unrestrained.

中文翻译：

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利用自动头室系统的气体通量来估算饲喂精加工饲料的肉牛的膳食能量值


维持膳食净能 (NEm) 和增重 (NEg) 可以通过基于现场表现或调整后的最终体重（根据胴体特征计算）的计算来估计。这些值通常称为性能调整 (pa) NEm (paNEm) 和 NEg (paNEg)。饮食的 NEm 和 NEg 也可以通过添加回收能量 (RE) 和自动头室系统 (AHCS) 产生的热量 (HP) 来估算，我们将其称为气体调节 (ga) NEm (gaNEm) 和NEg（gaNEg）。此外，Brouwer 方程中的 HP 需要估计尿氮 (UN) 排泄量，可以根据 N 摄入量、血液尿素 N、UN 浓度和尿肌酐来计算，或者可以将其归零。或者，可以使用基于呼吸商的替代方程来计算 HP。证明 pa 和 ga 衍生膳食能量值之间的一致性提供了验证使用 AHCS 进行能量实验的机会，并且之前尚未进行过这种比较。因此，本实验的目的是评估活体和屠体 paNEm 和 PANEg 与 GANEm 和 GANEg 之间的一致性，其中 HP 使用 4 种不同的方法计算。所采用的 4 种方法之间的 HP 估计值没有差异 (P = 0.99)，表明所研究的所有选项都是合适的。活体 paNEm 和 paNEg 与 gaNEm 和 gaNEg 的一致性高于胴体值 (CCC ≤ 0.84) [Lin 一致性相关系数 (CCC) = 0.91]。这些结果表明，研究人员可以实施 AHCS，以便对不受限制的育肥肉牛的膳食能量值提供良好的估计。