Heterosis, sex and breed differences in the fatty acid composition of muscle phospholipids in beef cattle

Longissimus dorsi muscle tissue was biopsied between the 12th and 13th ribs of 96 purebred Jersey, purebred Limousin and Jersey x Limousin crossbred calves at the age of 9-10 months. Fatty acids of the phospholipid fraction were extracted and analysed for sex and breed differences. Heterosis, additive and maternal variances were estimated. All calves grazed pasture in a single management group and were biopsied from the same anatomical site. Steer calves had significantly higher proportions of the 14:0, 14:1, 18:2, 20:3 fatty acids and less of the 16-di-methyl-acetal than heifer calves. Significant breed differences were observed: Limousin calves had the highest proportions of 16:0, 24:0 and saturated fatty acids (SFA), whereas Jersey x Limousin calves had the most 18:0 and elongation index. Dominant effects were evident in the proportions of 16:0, 18:0, SFA and elongation index. Additive genetic effects were significant in the proportions of 16:0, 18:0, 18:1n-9, total SFA and desaturation and elongation indices. Combined maternal and additive effects were significant for long chain polyunsaturated fatty acids 18:2, 20:3 and 20: 4.