Dual energy X-ray absorptiometry (DEXA) is an imaging modality that has been used to predict the computed tomography (CT)-determined carcass composition of multiple species, including sheep and pigs, with minimal inaccuracies, using medical grade DEXA scanners. An online DEXA scanner in an Australian abattoir has shown that a high level of precision can be achieved when predicting lamb carcass composition in real time. This study investigated the accuracy of that same online DEXA when predicting fat and lean percentages as determined by CT over a wide range of phenotypic and genotypic variables across 454 lambs over 6 kill groups and contrasted these results against the current Australian industry standard of grade-rule (GR) measurements to grade carcasses. Lamb carcasses were DEXA scanned and then CT scanned to determine CT Fat % and CT Lean %. All phenotypic traits and genotypic information, including Australian Sheep Breeding Values, were recorded for each carcass. Residuals of the DEXA predicted CT Fat % and Lean %, and the actual CT Fat % and Lean % were calculated and tested against all phenotypic and genotypic variables. Excellent overall precision was recorded when predicting CT Fat % (R2 = 0.91, RMSE = 1.19%). Small biases present for sire breed, sire type, dam breed, hot carcass weight and c-site eye muscle area could be explained by a regression paradox; however, biases among kill group (−0.73% to 1.01% for CT Fat %, −1.48% to 0.76% for CT Lean %) and the Merino sire type (0.36% for CT Fat %, −0.73% for CT Lean %) could not be explained by this effect. Over the large range of phenotypic and genotypic variation, there was excellent precision when predicting CT Fat % and CT Lean % by an online DEXA, with only minor biases, showing superiority to the existing Australian standard of GR measurements.

双能X射线吸收法（DEXA）是一种成像方法，已被用于使用医学级DEXA扫描仪来预测由计算机断层扫描（CT）确定的多种物种（包括绵羊和猪）的car体组成，且误差最小。澳大利亚屠宰场中的在线DEXA扫描仪表明，实时预测羔羊car体组成可以达到很高的精度。这项研究调查了同一在线在线DEXA在预测6个杀害组中454只羔羊的广泛表型和基因型变量的脂肪和瘦肉百分比时的准确性，并将这些结果与当前澳大利亚等级规则的行业标准进行了对比。 （GR）测量以对grade体进行分级。将羔羊尸体进行DEXA扫描，然后进行CT扫描以确定CT脂肪百分比和CT瘦肉百分比。记录每个recorded体的所有表型性状和基因型信息，包括澳大利亚绵羊育种值。DEXA的残基预测了CT脂肪百分比和瘦肉百分比，并计算了实际的CT脂肪百分比和瘦肉百分比，并针对所有表型和基因型变量进行了测试。预测CT脂肪百分比（R 2= 0.91，RMSE = 1.19％）。回归悖论可以解释公母，公母，水坝，热hot体重量和c位眼肌面积的小偏差。但是，杀死组之间存在偏见（CT脂肪百分比为-0.73％至1.01％，CT瘦肉百分比为-1.48％至0.76％）和美利奴牛类型（CT脂肪％为0.36％，CT瘦肉百分比为-0.73％）无法用这种效果来解释。在广泛的表型和基因型变异范围内，通过在线DEXA预测CT脂肪百分比和CT瘦肉百分比时，具有极好的精度，只有很小的偏差，显示出优于澳大利亚现有的GR测量标准。