Texas A&M University, Department of Animal Science, College Station 77843-2471.
J Anim Sci. 2013 Oct;91(10):4887-98. doi: 10.2527/jas.2011-4051. Epub 2013 Aug 26.
Twenty-six comparative slaughter studies were used (n = 752 animals) and coded within each experiment by gender (431 bulls, 204 steers, and 117 heifers) and breed (447 Nellore and 305 Bos indicus and Bos taurus crossbreds) to develop equations to predict the efficiency of use of ME to NE for growth (kg) and ME to NE for maintenance (km). The retained energy (RE) was regressed on ME intake (MEI) available for gain using orthogonal regression to obtain the kg within each experiment. The estimated kg was regressed on RE as protein (REp) according to the following equation: kg = a/(b + REp). Gender and breed effects were not tested because of limited number of experiments. The km was estimated as the intercept of the following equation: HP = β0 × e((β1 × MEI)), in which HP is heat production, β0 and β1 are coefficients, and e is the natural logarithm. The ME for maintenance (MEm) was computed assuming MEI equals to HP at maintenance. The km was obtained using the stepwise procedure of a multiple regression including ADG, empty body gain (EBG), empty BW (EBW), EBW(0.75), kg, and energy content in the EBW. A random coefficient model, assuming a random variation for study effects, was used to test breed and gender effects to identify the best model to estimate km. The overall equation to predict kg was 0.327 (±0.142)/[0.539 (±0.317) + REp], with an R(2) of 0.963. The equation to predict km was 0.513 (±0.024) + 0.173 (±0.061) × kg + a × EBG, R(2) = 0.92, in which a = 0.100 (±0.021) for B. indicus or a = 0.073 (±0.021) for crossbreds. Our results indicated that B. indicus were more efficient to use ME for maintenance. We concluded that km can be predicted from kg and EBG and that B. indicus × B. taurus crossbreds can affect km. Furthermore, kg can be predicted from REp and neither gender nor crossbreeding (B. indicus × B. taurus) affected kg. Because our database consisted of Nellore and B. indicus and B. taurus crossbreds, it is necessary to further evaluate differences between B. taurus and B. indicus regarding the kg.
使用了 26 项比较屠宰研究（n=752 头动物），并在每个实验中按性别（431 头公牛、204 头阉牛和 117 头小母牛）和品种（447 头尼里-拉菲牛和 305 头印度瘤牛和瘤牛杂交牛）进行编码，以制定预测 ME 用于生长（kg）和 ME 用于维持（km）的 NE 效率的方程。通过正交回归将保留能量（RE）回归到 ME 摄入量（MEI）中，以获得每个实验中的 kg。根据以下方程，将估计的 kg 回归到 RE 作为蛋白质（REp）：kg=a/(b+REp)。由于实验数量有限，因此未测试性别和品种效应。km 估计为以下方程的截距：HP=β0×e((β1×MEI))，其中 HP 是热产生，β0 和 β1 是系数，e 是自然对数。假设 MEI 等于维持时的 HP，即可计算出用于维持的 ME（MEm）。km 通过包括 ADG、空体增重（EBG）、空 BW（EBW）、EBW(0.75)、kg 和 EBW 中的能量含量在内的多元回归的逐步程序获得。使用随机系数模型，假设研究效应存在随机变化，以测试品种和性别效应，以确定估计 km 的最佳模型。预测 kg 的总体方程为 0.327(±0.142)/[0.539(±0.317)+REp]，R²=0.963。预测 km 的方程为 0.513(±0.024)+0.173(±0.061)×kg+a×EBG，R²=0.92，其中 a=0.100(±0.021) 用于印度瘤牛或 a=0.073(±0.021) 用于杂交牛。我们的结果表明，印度瘤牛在维持方面更有效地利用 ME。我们得出结论，km 可以从 kg 和 EBG 预测，印度瘤牛×瘤牛杂交牛可以影响 km。此外，kg 可以从 REp 预测，性别和杂交（印度瘤牛×瘤牛）都不影响 kg。由于我们的数据库由尼里-拉菲牛和印度瘤牛和瘤牛杂交牛组成，因此有必要进一步评估瘤牛和印度瘤牛之间关于 kg 的差异。
