Department of Animal and Food Sciences, Texas Tech University, Lubbock, TX 79409-2141, USA.
J Anim Sci. 2010 Feb;88(2):756-66. doi: 10.2527/jas.2009-1951. Epub 2009 Sep 25.
The objective of this study was to compare the fatty acid (FA) composition of intramuscular fat from the LM of 3 divergent breeds of cattle: Angus (AN, n = 9), Brahman (BR, n = 7), and Romosinuano (RM, n = 11). Cattle were blocked by breed and finished 129 d before slaughter in one year and 157 d in the next year. Longissimus muscle samples were collected from each carcass between the 10th and 13th ribs, trimmed of external fat, frozen in liquid nitrogen, homogenized, and used for fat extraction, using a modified Folch procedure. Extracted fat was analyzed for FA by using a GLC system with an HP-88 capillary column. Fatty acid composition was expressed using both a normalized percentage (%) and gravimetric calculation (mg/g of fresh muscle tissue) in relation to degree of saturation, which was determined using a saturation index (ratio of total SFA to total unsaturated FA). Crude fat determination revealed that LM from AN purebred cattle had the greatest amount of intramuscular fat (7.08%; P = 0.001). Although intramuscular fat of LM from RM contained a reduced percentage of total SFA (P = 0.002) compared with AN, it had the greatest percentage of total PUFA (P < 0.001 and P = 0.020). The percentages of total MUFA were similar among the 3 breeds (P = 0.675). The gravimetric calculation, a measure of actual FA concentration, showed significantly greater concentrations of SFA (26.67 mg/g), MUFA (26.50 mg/g), and PUFA (2.37 mg/g) in LM from AN cattle, as compared with LM from BR and RM cattle (P < 0.001). Interestingly, BR purebreds had the least PUFA concentration (1.49 mg/g; P <or= 0.001) in the LM, although their intramuscular fat content was similar to that of RM (P = 0.924). Regardless of breed, the MUFA proportion was always the greatest (47.58%; P <or= 0.005), whereas PUFA was the least contributor to FA composition (1.49 to 2.37 mg/g and 4.36 to 8.78%; P < 0.001). Beef LM fatty acid composition was characterized by palmitic and oleic acids being the most abundant FA (P < 0.001). These results suggested a genetic variation in FA synthesis and deposition among breeds that influenced both marbling and its composition.
本研究的目的是比较 3 个不同品种牛的肌肉内脂肪的脂肪酸（FA）组成：安格斯牛（AN，n = 9）、婆罗门牛（BR，n = 7）和罗曼诺夫牛（RM，n = 11）。牛按品种分组，在一年中的 129 天和第二年的 157 天结束育肥。在第 10 至 13 肋骨之间采集每个胴体的背最长肌样本，去除外部脂肪，在液氮中冷冻，均质化，然后用改良的 Folch 法提取脂肪。使用带有 HP-88 毛细管柱的 GLC 系统分析提取的脂肪中的 FA。脂肪酸组成既以归一化百分比（%）表示，也以与饱和度有关的重量计算（mg/g 新鲜肌肉组织）表示，饱和度通过饱和度指数（总饱和脂肪酸与总不饱和脂肪酸的比值）确定。粗脂肪测定显示，纯安格斯牛的背最长肌含有最多的肌肉内脂肪（7.08%；P = 0.001）。尽管与 AN 相比，RM 背最长肌中的总 SFA 百分比降低（P = 0.002），但它的总多不饱和脂肪酸（PUFA）百分比最高（P < 0.001 和 P = 0.020）。3 个品种的总 MUFA 百分比相似（P = 0.675）。重量计算，即实际 FA 浓度的度量，显示 AN 牛的背最长肌中的 SFA（26.67 mg/g）、MUFA（26.50 mg/g）和 PUFA（2.37 mg/g）浓度显著高于 BR 和 RM 牛的背最长肌（P < 0.001）。有趣的是，BR 纯系的背最长肌中 PUFA 浓度最低（1.49 mg/g；P <or= 0.001），尽管其肌肉内脂肪含量与 RM 相似（P = 0.924）。无论品种如何，MUFA 的比例总是最大（47.58%；P <or= 0.005），而 PUFA 对 FA 组成的贡献最小（1.49 至 2.37 mg/g 和 4.36 至 8.78%；P < 0.001）。牛肉背最长肌的脂肪酸组成特征是棕榈酸和油酸是最丰富的 FA（P < 0.001）。这些结果表明，品种间的 FA 合成和沉积存在遗传变异，这影响了大理石花纹及其组成。
