Robinson D L, McDonald C A, Hammond K, Turner J W
Animal Breeding and Genetics Unit, University of New England, Armidale, NSW, Australia.
J Anim Sci. 1992 Jun;70(6):1667-76. doi: 10.2527/1992.7061667x.
The establishment and evaluation of an assessment system to accredit sonographers for measuring the carcass traits of subcutaneous fat depths and longissimus muscle area (LMA) on potential breeding animals by real-time ultrasound is described. Repeatability of operators, variation between the animal's left and right sides, and variations in technique were assessed from measurements and repeat measurements of 30 cattle by up to eight operators at three testing sessions. Accuracy of carcass data was determined by repeatability of measurements, variability between measurers, between left and right sides of the carcass, and variation due to handling and dressing procedures. Correlations with carcass data averaged .92 for rump fat, .90 for rib fat, and .87 for LMA. Residual SD averaged .81 mm, .88 mm, and 5.1 cm2. A very experienced sonographer can measure LMA only marginally less accurately than it can be measured on the carcass. In Session 3, the SE between repeat fat measurements for accredited sonographers averaged .43 mm, indicating that fat depths can be measured more accurately, but when comparing measurements from different operators, adjustments may be required for differences in technique, otherwise overall accuracy will be about the same, approximately 1 mm. Scanned rump fat measurements were consistently approximately 20% higher than on the chilled, hanging carcass 24 h after slaughter; after applying the standard correction factor of 1.17, LMA measurements were similar. Scan and carcass rib fat measurements were similar for animals with less than or equal to 10 mm of fat cover, above which carcass measurements tended to be higher.
本文描述了一种评估系统的建立与评估，该系统用于认可超声检查人员通过实时超声测量潜在育种动物皮下脂肪深度和背最长肌面积（LMA）等胴体性状的能力。通过多达八名操作人员在三个测试阶段对30头牛进行测量和重复测量，评估了操作人员的重复性、动物左右侧之间的差异以及技术差异。通过测量的重复性、测量人员之间的变异性、胴体左右侧之间的变异性以及处理和屠宰程序导致的变异性来确定胴体数据的准确性。与胴体数据的相关性，臀部脂肪平均为0.92，肋部脂肪为0.90，LMA为0.87。剩余标准差平均为0.81毫米、0.88毫米和5.1平方厘米。一位经验非常丰富的超声检查人员测量LMA的准确性仅略低于在胴体上的测量。在第三阶段，经认可的超声检查人员重复测量脂肪的标准误平均为0.43毫米，这表明脂肪深度可以测量得更准确，但在比较不同操作人员的测量结果时，可能需要对技术差异进行调整，否则总体准确性将大致相同，约为1毫米。扫描的臀部脂肪测量值始终比屠宰后24小时冷藏悬挂胴体上的测量值高约20%；应用1.17的标准校正因子后，LMA测量值相似。对于脂肪覆盖小于或等于10毫米的动物，扫描和胴体肋部脂肪测量值相似，超过该值胴体测量值往往更高。
