SEX AND BREED DIFFERENCES IN THE FATTY ACID COMPOSITION OF MUSCLE PHOSPHOLIPIDS IN CROSSBRED CATTLE

Phospholipid data from the Longissimus dors i (eye muscle) of 117 weaners across 7 cattle genotypes were analysed. The aim was to investigate sex and breed differences in fatty acid composition of muscle phospholipids in an entirely grass-fed management situation. Results showed that sex was a significant source of variation in the levels of 18: ln-9, total monounsaturated fatty acids (MUFA) and calculated A’-desaturase enzyme activity index. Heifers had higher percentages in all cases than steers. All the other individual fatty acids and the summations of their proportions did not differ between the sexes. Significant breed differences were apparent in 18: ln-9, 18:3n-3, MUFA and A’-desaturase enzyme index. Wagyu and Belgian Blue crosses had the highest proportion of 18: ln-9 and Hereford the lowest. Jersey crosses and Hereford breeds had the highest 18:3n-3 levels and Belgian Blue the lowest. A’-desaturase enzyme index was highest in the Wagyu crosses. There were no other breed differences detected in all the other individual fatty acids and their summations. This study suggests that in weaners, the fatty acid composition of muscle lipids differs between breeds and sexes. The magnitude of the differences is, nevertheless, more reflected in the adipose tissue than in the muscle phospholipids. Also, Wagyu and Belgian Blue genotypes produced muscles with the most monounsaturated fatty acids