Biohydrogenation intermediates are differentially deposited between polar and neutral intramuscular lipids of lambs

The deposition of C-18 fatty acids (FA), especially in rumen biohydrogenation intermediates, was studied using 36 lambs fed four diets with graded proportions of sunflower oil (SO) and linseed oil (LO). Lambs were fed one of four diets consisting on dehydrated lucerne with either:6% SO, 4% SO plus 2% LO, 2% SO plus 4% LO and 6% LO. The profile of C-18 FA was greatly affected by replacement of SO with LO in both lipid fractions. In PL, oil replacement led to an extensive substitution of 18:2n-6 with 18:3n-3 and cis-9 18:1, resulting in a fairly constant degree of unsaturation of C-18 FA in membrane PL. C-18 FA were differentially incorporated in NL and PL. Cis-isomers like cis-11; cis-12; cis-15 18:1 and cis-12, cis-15 18:2 were preferentially incorporated in PL with the exception of cis-9, cis-15 18:2. Trans C-18 FA, including CLA isomers, were preferentially incorporated in NL with the exception of cis-11, trans-13 18:2. The preferential deposition of biohydrogenation derived trans C-18 FA, including CLA isomers in NL, suggests that their potential to change membrane FA composition and structure is low.