Berg E P, Neary M K, Forrest J C, Thomas D L, Kauffman R G
Department of Animal Sciences, Purdue University, West Lafayette, IN 47907-1151, USA.
J Anim Sci. 1997 Sep;75(9):2433-44. doi: 10.2527/1997.7592433x.
Accurate price signals are essential for producers of American lamb to ensure production of uniformly lean animals. Development of carcass merit-pricing systems will require the use of objective technology for assessing carcass composition or lean distribution. The objective of this study was to evaluate electronic technologies for accurate determination of lamb carcass composition. Lambs (n = 106) were selected as a representation of U.S. market lambs that transcended geographic location, sex, breed, carcass weight, yield grade, and production system. The independent variables used to predict lamb composition varied with the technology. The electronic technologies tested included realtime ultrasound, optical reflectance probe, bioelectrical impedance analysis, and electromagnetic scanning (TOBEC). All technologies, except realtime ultrasound, were tested on warm (prerigor) carcasses and repeated after a 24-h chill. Longitudinal ultrasonic scans of fat and muscle tissue depth and grading probe fat depths were marginal predictors of proportional carcass yield. The TOBEC measurements often accounted for more variability associated with kilograms of dissected lean and percentage of carcass lean than did carcass weight. Equations from TOBEC measurements were the most accurate predictors of weight and percentage of dissected and fat-free lean. Bioelectrical impedance measurements of resistance and reactance combined with carcass weight were also good predictors of carcass composition. Prediction of carcass lean distribution by measures of TOBEC were the most accurate for prediction of leg lean. The implications of usefulness of these technologies will depend on the commitment of the U. S. sheep industry in development of a lamb price discovery system based on carcass composition.
准确的价格信号对于美国羊肉生产商确保生产出瘦肉均匀的羊至关重要。胴体品质定价系统的开发将需要使用客观技术来评估胴体组成或瘦肉分布。本研究的目的是评估电子技术对准确测定羊胴体组成的效果。选取了106只羊作为美国市场羊的代表，这些羊跨越了地理位置、性别、品种、胴体重、产量等级和生产系统。用于预测羊组成的自变量因技术而异。所测试的电子技术包括实时超声、光学反射探头、生物电阻抗分析和电磁扫描（全身体液导电率测定仪）。除实时超声外，所有技术均在温热（宰后僵直前期）胴体上进行测试，并在冷藏24小时后重复测试。脂肪和肌肉组织深度的纵向超声扫描以及分级探头脂肪深度是胴体产肉比例的边际预测指标。与胴体重相比，全身体液导电率测定仪的测量结果通常能解释更多与分割瘦肉千克数和胴体瘦肉百分比相关的变异性。全身体液导电率测定仪测量得出的方程是分割瘦肉和去脂瘦肉重量及百分比的最准确预测指标。电阻和电抗的生物电阻抗测量值与胴体重相结合也是胴体组成的良好预测指标。通过全身体液导电率测定仪测量来预测胴体瘦肉分布，对腿部瘦肉的预测最为准确。这些技术的实用性所带来的影响将取决于美国养羊业在开发基于胴体组成的羊肉价格发现系统方面的投入程度。
