Backfat fatty acid evolution in swine fed diets high in either cis-monounsaturated, trans, or (n-3) fats.

To evaluate the effects of dietary fats on the evolution of the fatty acid profile of swine backfat, 30 castrated Landrace x Duroc pigs averaging 26 kg were assigned three diets with 4% added pomace oil (O), hydrogenated fat (H), or linseed oil (L). Subcutaneous fat samples were taken from biopsies at 0, 17, 31, and 60 d, and at 24 h postmortem when pigs averaged 95 kg live weight at 82 d on trial. On d 17, saturated fatty acid (SFA) content was 2% lower for the O diet than for H and L (P < .089). There was a linear increase in SFA at a monthly rate of 2% in the three diets. The increase was mainly due to 18:0; palmitic acid percentages showed no variation. Pigs fed the O diet experienced exponential increases in monounsaturated fatty acids (MUFA), especially until d 17 (P < .001). In pigs fed the H or L diets, MUFA contents decreased at a monthly rate of 2.40%, and the same happened with oleic acid contents. Diets rich in (n-3) (L) and trans-fatty acids (H) caused exponential increases in swine backfat contents of total (n-3) and total trans, respectively. At d 31 (P < .001), 72 to 73% of the maximum contents had been reached. Contents for 20:3(n-3), 20:5(n-3), and 22:5(n-3) follow a pattern similar to that of their precursor 18:3(n-3), showing an exponential increase in pigs fed the L diet, and contents for H and O treatments were lower (P < .001). The three diets caused a linear decrease in (n-6) fatty acid contents throughout the 82-d trial.