Enser M, Hallett K G, Hewett B, Fursey G A, Wood J D, Harrington G
Division of Food Animal Science, School of Veterinary Science, University of Bristol, Langford, Bristol, BS18 7DY, UK.
Meat Sci. 1998 Jul;49(3):329-41. doi: 10.1016/s0309-1740(97)00144-7.
Although ruminant meats normally have a low ratio of polyunsaturated fatty acids (PUFA) to saturated fatty acids (P:S ratio), the muscle contains a range of C(20) and C(22) PUFA of both the n-6 and n-3 series of potential significance in human nutrition. However, information on the amounts of these fatty acids in muscle and how they are modified by production system is limited In this study, the content and composition of fatty acids was determined in several muscles from beef steers fed grass (grazed) and bulls fed cereal concentrates. These are the two main types of beef production in the UK and Europe. Muscle fatty acids were also determined in lambs fed grass (grazed on pasture). The total fatty acid content of all muscles studied was less than 35 g kg(-1). The percentages in total fatty acids of all n-3 PUFA were higher in muscles from steers fed grass than from bulls fed concentrates whereas all n-6 PUFA were higher in the latter. The gluteobiceps muscle contained the largest amounts of fatty acids including PUFA and the m. longissimus dorsi the least amounts of PUFA in beef and lamb, and m. longissimus contained the lowest percentages of PUFA. Arachidonic acid was the major fatty acid in the C(20) + C(22) PUFA in beef from both production systems with twice as much in muscles from bulls fed concentrates. The P:S ratios were higher in the latter animals, range 0.21-0.34 compared with 0.08-0.13 in the steers fed grass. However, the n6:n-3 ratio was much less desirable in the bulls, 15.6-20.1 compared with 2.0-2.3 in the steers fed grass. These effects of production system in ruminants are larger than previously reported. Lamb muscle P:S ratios resembled those in grass-fed beef but the n-6:n-3 ratios were lower. The percentage of trans unsaturated 18:1 fatty acids was similar in both cattle production systems but lamb muscles contained twice as much as beef. Although the concentrations of the C(20) and C(22) PUFA are much lower than in fish, maintaining high n-3 levels in ruminant meats through grass feeding may be advantageous in human nutrition since meat is more widely consumed.
尽管反刍动物肉类中多不饱和脂肪酸（PUFA）与饱和脂肪酸的比例通常较低（P:S 比值），但其肌肉中含有一系列 n-6 和 n-3 系列的 C(20) 和 C(22) 多不饱和脂肪酸，对人类营养具有潜在重要意义。然而，关于这些脂肪酸在肌肉中的含量以及它们如何因生产系统而改变的信息有限。在本研究中，测定了以草为食（放牧）的肉牛和以谷物浓缩物为食的公牛的几块肌肉中的脂肪酸含量和组成。这是英国和欧洲两种主要的牛肉生产类型。还测定了以草为食（在牧场放牧）的羔羊肌肉中的脂肪酸。所有研究肌肉的总脂肪酸含量均低于 35 g kg(-1)。在以草为食的肉牛肌肉中，所有 n-3 多不饱和脂肪酸在总脂肪酸中的百分比高于以浓缩物为食的公牛，而所有 n-6 多不饱和脂肪酸在后者中含量更高。臀二头肌含有包括多不饱和脂肪酸在内的最多脂肪酸，而牛肉和羊肉中的背最长肌含有的多不饱和脂肪酸最少，背最长肌中多不饱和脂肪酸的百分比最低。花生四烯酸是两种生产系统牛肉中 C(20) + C(22) 多不饱和脂肪酸中的主要脂肪酸，在以浓缩物为食的公牛肌肉中的含量是其两倍。后者动物的 P:S 比值更高，范围为 0.21 - 0.34，而以草为食的肉牛为 0.08 - 0.13。然而，公牛的 n6:n-3 比值远不如以草为食的肉牛理想，分别为 15.6 - 20.1 和 2.0 - 2.3。反刍动物生产系统的这些影响比之前报道的更大。羔羊肌肉的 P:S 比值与以草为食的牛肉相似，但 n-6:n-3 比值更低。两种肉牛生产系统中反式不饱和 18:1 脂肪酸的百分比相似，但羔羊肌肉中的含量是牛肉的两倍。尽管 C(20) 和 C(22) 多不饱和脂肪酸的浓度远低于鱼类，但通过草饲在反刍动物肉类中维持高 n-3 水平在人类营养方面可能具有优势，因为肉类的消费更为广泛。
