Intramuscular fat (IMF) % is an important measure of pork eating quality, with reduced IMF % linked to the selection of pigs with low backfat P2 thickness and more muscular genotypes over several decades. This experiment tested the association of IMF % from the M. longissimus thoracis et lumborum of 345 pigs at three abattoirs (Sites) with computed tomography (CT) determined carcass composition (% lean or fat), accredited abattoir measures of P2 backfat (mm) (Hennessy Grading Probe, AutoFom III and PorkScan Lite) and the lean % output from abattoir devices (Hennessy Grading Probe, AutoFom III and PorkScan Plus). There was a negative relationship between carcass CT lean % with IMF % at all Sites (P < 0.05), with the strength of this relationship varying between Sites. The strongest relationship was demonstrated at Site 1 (R2 0.30, RMSE 0.59), and across a 4 standard deviation range in the carcass lean % at each Site, resulted in a decrease in loin IMF % of 1.56, 0.44 and 0.80. There was a positive relationship of carcass CT fat % with IMF %, with similar, albeit slightly stronger relationship to IMF than with CT lean %. In contrast, only one of the three Sites with an accredited P2 measurement device demonstrated a significant association (P < 0.05) with IMF %. This is the first time the associations of IMF % with carcass CT composition has been assessed alongside that of P2 backfat measures from commercially deployed abattoir devices. Given P2 backfat is the key industry measure on which carcass value is determined in Australia, this experiment demonstrates the limitations that P2 has in measuring and monitoring the associations of carcass lean and fat % with IMF. Ideally, an independent measure of IMF % would allow for independent selection for lean % and IMF %, however there is currently no commercial device that can measure pork IMF %.

中文翻译：

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澳大利亚猪里脊肉的肌内脂肪百分比与计算机断层扫描瘦肉和脂肪百分比的关系比屠宰场测量的 P2 和瘦肉百分比更强


肌内脂肪 （IMF） % 是衡量猪肉食用质量的重要指标，IMF % 的降低与几十年来选择背膘 P2 厚度低和肌肉基因型较多的猪有关。本实验测试了三个屠宰场（地点）的 345 头猪的 M. longissimus thoracis et lumborum 的 IMF % 与计算机断层扫描 （CT） 确定的胴体成分（% 瘦肉或脂肪）、经认可的屠宰场 P2 背膘测量值 （mm） 的关联（Hennessy Grading Probe、AutoFom III 和 PorkScan Lite）和屠宰场设备的瘦肉百分比输出（Hennessy Grading Probe， AutoFom III 和 PorkScan Plus）。所有地点的胴体 CT 瘦肉率与 IMF % 之间存在负相关 （P < 0.05），这种关系的强度因地点而异。在站点 1 （R2 0.30，RMSE 0.59） 表现出最强的关系，并且在每个站点的胴体瘦肉百分比的 4 个标准差范围内，导致里脊肉 IMF % 下降 1.56、0.44 和 0.80。胴体 CT 脂肪百分比与 IMF % 呈正相关，与 IMF 的关系相似，但略强于 CT 瘦肉百分比。相比之下，在拥有经认可的 P2 测量设备的三个站点中，只有一个显示出与 IMF % 的显著关联 （P < 0.05）。这是首次评估 IMF % 与胴体 CT 成分的关联以及商业部署屠宰场设备的 P2 背膘测量值的关联。鉴于 P2 背膘是澳大利亚确定胴体价值的关键行业指标，该实验证明了 P2 在测量和监测胴体瘦肉和脂肪百分比与 IMF 的关联方面的局限性。 理想情况下，IMF % 的独立测量将允许独立选择瘦肉 % 和 IMF %，但目前没有可以测量猪肉 IMF % 的商业设备。