Effects of feeding pigs increasing levels of C 18:1 trans fatty acids on fatty acid composition of backfat and intramuscular fat as well as backfat firmness

Forty Large White pigs were fed from 30 kg to 103 kg body mass on diets supplemented with 6% of pure high-oleic sunflower oil (HO) or HO plus increasing amounts of partially hydrogenated rape seed oil (HR; 1.85%, 3.70%, 5.55%), containing high levels of Delta6 to Delta11 C 18:1 trans fatty acid isomers. Increasing dietary C 18: trans fatty acids resulted in a linear increase in C 18:1 trans fatty acids and conjugated linoleic acid (cis-9, trans-11 CLA) in backfat (BF) as well as in neutral lipids (NL) and phospholipids (PL) of M. long. dorsi. Thus, the rate of bioconversion of trans vaccenic acid (TVA) into CLA and incorporation of C 18:1 trans and CLA into pig adipose tissue was not limited up to 25 g total C 18:1 trans fatty acids including 3.3 g of TVA per kg feed. BF was higher in C 18:1 trans fatty acids and CLA than M. long. dorsi NL and PL. In BF and NL the sum of saturated fatty acids (SFA) increased with increasing dietary amounts of HR, while in PL SFA were reduced. Thus, according to their physical properties, C 18:1 trans fatty acids partly replaced SFA in PL. Firmness of backfat was also significantly increased (P < 0.05) with increasing amounts of HR in feed.