Effect of double-muscling in Belgian Blue young bulls on the intramuscular fatty acid composition with emphasis on conjugated linoleic acid and polyunsaturated fatty acids

The effect of double-muscling (DM) genotype (double-muscling, mh/mh; heterozygous, mh/+; normal, +/+) of Belgian Blue (BB) young bulls on the intramuscular fatty acid composition, in particular conjugated linoleic acid (CLA) and polyunsaturated fatty acids (PUFA) was examined in five different muscles. The relative fatty acid composition showed only minor differences between muscles within genotypes. However, the DM genotype had a large effect on both the intramuscular total fatty acid content and on the relative fatty acid composition. Across muscles, the mh/mh animals had a lower total fatty acid content compared with the +/+ animals (907 v. 2656 mg/100 g muscle; P < 0.01) and a higher PUFA proportion in total fatty acids (27.5 v. 11.3 g/100 g total fatty acids; P < 0.001), resulting in a higher PUFA/saturated fatty acid ratio (0.55 v. 0.18; P < 0.01) and a lower n-6/n-3 ratio (5.34 v. 6.17; P < 0.01). The heterozygous genotype was intermediate between the two homozygous genotypes. The relative CLA content was similar in the mh/mh and +/+ genotypes and approximated 0.4 to 0.5 g/100 g total fatty acids. From the data it is further suggested that differences in the metabolism of the n-3 and n-6 fatty acids could exist between DM genotypes.