EFFECT OF ANATOMICAL LOCATION ON THE COMPOSITION OF FATTY-ACIDS IN DOUBLE-MUSCLED BELGIAN-BLUE COWS

Double-muscled cows of the Belgian Blue breed, ranging from ca. 680 to 880 kg live weight were slaughtered and various fat depots sampled fo r lipid analysis. Subcutaneous fat (SCF), intermuscular fat in m, serr atus (IMF1) and m. transversalis (IMF2), kidney fat (KF) and intramusc ular fat in m, longissimus thoracis (IMF3) were sampled. In IMF3 sampl es, polar lipids were separated from other lipid classes by thin layer chromatography. Both the proportions (w/w %) and gravimetric concentr ations (mg g(-1) of sample) of long-chain fatty acids were determined in total lipids of SCF IMF1, IMF2, KF and in lipid classes of IMF3 by gas chromatography. The greatest concentration of total fatty acids wa s found in KF (777.6 +/- 82.6 mg g(-1)), followed by SCF (721.3 +/- 92 .2 mg g(-1)), IMF2 (709.8 +/- 72.5 mg g(-1)) and IMF1 (682.1 +/- 71.6 mg g(-1). Triacylglycerol and polar lipid fatty acid content of m. lon gissimus thoracis (IMF3) were respectively 8.1 +/- 3.3 and 3.1 +/- 0.6 mg g(-1). Fatty acid content, particularly the triacylglycerol fatty acid content in IMF3, increased (p < 0.01) with increasing carcass fat content. Polar lipid fatty acids in IMF3 contained a higher proportio n of polyunsaturated fatty acids (32.6 +/- 4.8%) and lower proportion of saturated fatty acids (274 +/- 5.0%) compared to the triacylglycero l fatty acid fraction (p < 0.01), which may reflect a prerequisite for proper membrane functioning. Internal fat depots were more saturated (p < 0.01) compared to SCF. The proportion of monounsaturated fatty ac ids differed (p < 0.01) between IMF1 and IMF2, possibly reflecting dif ferences in muscle activity and functioning. Oleic (C18:1) and stearic (C18:0) acids comprised more than 60% of the total fatty acids in all anatomical locations. (C) 1998 Elsevier Science Ltd. All rights reser ved.