Griffin D B, Savell J W, Recio H A, Garrett R P, Cross H R
Department of Animal Science, Texas Agricultural Experimental Station, Texas A&M University, College Station 77843-2471, USA.
J Anim Sci. 1999 Apr;77(4):889-92. doi: 10.2527/1999.774889x.
We evaluated 20 slaughtered cattle with ultrasound before hide removal to predict fat thickness and ribeye area at the 12th rib for possible use in carcass composition prediction. Carcasses were fabricated into boneless subprimals that were trimmed progressively from 2.54 to 1.27 to .64 cm maximum fat trim levels. Stepwise regression was used to indicate the relative importance of variables in a model designed to estimate the percentage of boneless subprimals from the carcass at different external fat trim levels. Variables included those obtained on the slaughter floor (ultrasound fat thickness and ribeye area; estimated percentage of kidney, pelvic, and heart [KPH] fat; and warm carcass weight) and those obtained from carcasses following 24 h in the chill cooler (actual fat thickness, actual ribeye area, estimated percentage of KPH fat, warm carcass weight, and marbling score). At all different subprimal trim levels, percentage KPH was the first variable to enter the model. In the models using measures taken on the slaughter floor, ultrasound fat thickness was the only other variable to enter the model. Ultrasound fat thickness increased R2 and decreased residual standard deviation (RSD) in models predicting subprimals at 2.54-cm maximum fat trim; however, at 1.27- and .64-cm trim levels, R2 and RSD increased. Models using the same two variables (except actual fat instead of ultrasound) in the cooler were similar to those using data from the slaughter floor. However, as more cooler measurement variables entered the models, R2 increased and RSD decreased, explaining a greater amount of the variation in the equation. Ultrasonic evaluation on the slaughter floor may be of limited application compared with the greater accuracy found in chilled carcass assessment.
我们在剥皮前对20头屠宰牛进行了超声评估，以预测第12肋骨处的脂肪厚度和肋眼面积，以便用于胴体组成预测。将胴体加工成去骨的主要切块，从最大脂肪修整水平2.54厘米逐步修整到1.27厘米再到0.64厘米。逐步回归用于表明在一个旨在估计不同外部脂肪修整水平下胴体去骨主要切块百分比的模型中变量的相对重要性。变量包括在屠宰场获得的那些（超声脂肪厚度和肋眼面积；肾脏、骨盆和心脏[KPH]脂肪的估计百分比；以及热胴体重）以及在冷却库中放置24小时后的胴体获得的那些（实际脂肪厚度、实际肋眼面积、KPH脂肪的估计百分比、热胴体重和大理石花纹评分）。在所有不同的主要切块修整水平下，KPH百分比是第一个进入模型的变量。在使用屠宰场测量数据的模型中，超声脂肪厚度是唯一进入模型的其他变量。在预测最大脂肪修整为2.54厘米的主要切块时，超声脂肪厚度增加了R2并降低了剩余标准差（RSD）；然而，在1.27厘米和0.64厘米的修整水平下，R2和RSD增加了。在冷却库中使用相同两个变量（除了实际脂肪而不是超声）的模型与使用屠宰场数据的模型相似。然而，随着更多冷却库测量变量进入模型，R2增加而RSD降低，解释了方程中更大比例的变化。与在冷却胴体评估中发现的更高准确性相比，屠宰场的超声评估应用可能有限。
