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 equation requires an estimate of urinary 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 a 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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利用来自自动头室系统的气体通量来估计饲喂育肥日粮的肉牛的膳食能量值


用于维持的膳食净能量 （NEm） 和增重 （NEg） 可以使用基于现场表现的计算或调整后的最终体重来估计，后者是根据胴体特征计算的。这些值通常称为性能调整 （pa）、NEm （paNEm） 和 NEg （paNEg）。饮食的 NEm 和 NEg 也可以通过添加来自自动头室系统 （AHCS） 的回收能量 （RE） 和产热 （HP） 来估计，我们将其称为气体调整 （ga） NEm （gaNEm） 和 NEg （gaNEg）。此外，Brouwer 方程的 HP 需要估计尿氮 （UN） 排泄量，可以根据 N 摄入量、血尿素 N、UN 浓度和尿肌酐计算，也可以归零。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 衍生的膳食能量值之间的一致性为验证使用 AHCS 进行能量实验提供了机会，并且以前没有进行过这种比较。因此，本实验的目的是评估活体和胴体 paNEm 和 paNEg 与 gaNEm 和 gaNEg 之间的一致性，其中 HP 是使用 4 种不同的方法计算的。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 paNEm 和 paNEg 与 gaNEm 和 gaNEg 的一致性 （Lin's 相关相关系数 [CCC] = 0.91） 高于胴体值 （CCC ≤ 0.84）。这些结果表明，研究人员可以实施 AHCS 来提供对无约束肉牛育肥的膳食能量值的良好估计。