The objective was to determine the amount and variability of intramuscular fat in a pork loin attributable to anatomical chop location, sex, and sire line. Pigs were sired by commercially available terminal Duroc boars selected for meat quality (MQ; n = 96) or lean growth (LG; n = 96) and equally split between barrows and gilts. After slaughter and fabrication, bone-in chops were removed from four locations of each left-side loin (A = 6 ^th rib, B = 10 ^th rib, C = last rib, D = 4 ^th lumbar vertebrae). An adjacent pair of chops from each location was collected and evaluated for visual color and marbling, subjective firmness, moisture and extractable lipid (IMF) (anterior chop), and Warner-Bratzler shear force (posterior chop). Data were analyzed using the MIXED procedure of SAS as a split-plot design. Homogeneity of variances was tested on raw data using Levene’s test of the GLM procedure, and found to be heterogeneous. Thus a 2-variance model was fit using the REPEATED statement of the MIXED procedure, grouped by pig. The mivque(0) option of the VARCOMP procedure was used to calculate the proportion of variability each individual factor contributed to total variance. Barrows (3.64%) produced chops with greater (P & 0.01) IMF content than gilts (3.20%) and barrows (2.14) had greater (P & 0.01) IMF variability than gilts (1.23). Chops from MQ pigs (4.02%) exhibited greater (P & 0.01) IMF content than LG (2.82%) and MQ (1.76) had greater IMF variability (P & 0.01) than LG pigs (0.97). Chops from location A (3.80%) and D (3.77%) had greater IMF than B (3.34%; P & 0.01), and A, B, and D had greater IMF than C (2.77%; P & 0.01). Variances of IMF also differed (A = 1.44, B = 1.59, C = 1.05, D = 2.18; P = 0.01) across chop locations. Of the variability in IMF, 33.0% was attributed to sire line, 10.16% to chop location and 4.01% to sex, with 52.83% not accounted for by these three factors. Location A chops were the most (P & 0.01) tender (2.57 kg) and C chops the least (P & 0.01) tender (2.93 kg) while B and D chops were intermediate and not different from each other. No differences in variability (P = 0.40) of tenderness were observed among chop locations (A = 0.31, kg B = 0.24 kg, C = 0.24 kg, D = 0.23 kg). These results demonstrated that variability in tenderness values did not reflect the variability of IMF. In conclusion, chop location, sex, and sire line all contribute to the amount and variability of pork loin marbling.

中文翻译：

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使用来自两个父系的公猪和小母猪表征整个猪腰肉肌肉内脂肪沉积的数量和变异性。

目的是确定猪腰肉中肌肉内脂肪的数量和变异性，这可归因于解剖位置、性别和父系。猪是由市售的杜洛克终端公猪生产的，这些公猪的肉质量（MQ；n = 96）或瘦肉生长（LG；n = 96）并在公猪和小母猪之间平均分配。屠宰和加工后，从每个左侧腰部的四个位置（A = 6 ^th肋骨，B = 10 ^th肋骨，C = 最后肋骨，D = 4 ^th肋骨）去除带骨排骨腰椎）。收集来自每个位置的相邻两排，并评估视觉颜色和大理石花纹、主观硬度、水分和可提取脂质 (IMF)（前排）和 Warner-Bratzler 剪切力（后排）。使用 SAS 的混合程序作为裂区设计分析数据。使用 Levene 对 GLM 程序的检验对原始数据进行了方差同质性测试，发现是异质性的。因此，使用 MIXED 过程的 REPEATED 语句拟合 2 方差模型，按猪分组。VARCOMP 程序的 mivque(0) 选项用于计算每个单独因素对总方差的贡献比例。母猪(3.64%) 生产的猪排的IMF 含量高于( P & 0.01) 母猪 (3.20%) 和公猪 (2.14) 的更高 ( P & 0.01)P & 0.01) IMF 变异性比后备母猪 (1.23)。MQ 猪（4.02%）的IMF 含量（P & 0.01）高于 LG（2.82%），MQ（1.76）的 IMF 变异性（P & 0.01）高于 LG 猪（0.97）。来自位置 A (3.80%) 和 D (3.77%) 的印章的 IMF 大于 B (3.34%；P & 0.01)，并且 A、B 和 D 的 IMF 大于 C (2.77%；P & 0.01)。IMF 的方差也不同（A = 1.44，B = 1.59，C = 1.05，D = 2.18；P= 0.01) 跨越切割位置。IMF的变异性中，33.0%归因于父系，10.16%归因于位置，4.01%归因于性别，其中52.83%未由这三个因素引起。位置 A 排骨最嫩（P & 0.01）（2.57 公斤），C 排排最不嫩（P & 0.01）（2.93 公斤），而 B 和 D 排排中间，彼此没有区别。在剁碎位置（A = 0.31，kg B = 0.24 kg，C = 0.24 kg，D = 0.23 kg）之间没有观察到压痛的变异性（P = 0.40）差异。这些结果表明，嫩度值的可变性并未反映 IMF 的可变性。总而言之，猪排位置、性别和种系都会影响猪腰肉大理石花纹的数量和变异性。