Extruded linseed and rapeseed both influenced fatty acid composition of total lipids and their polar and neutral fractions in longissimus thoracis and semitendinosus muscles of finishing Normand cows.

ABSTRACT

The effects of extruded linseed and rapeseed on lipids and FA composition of total, polar and neutral lipids of longissimus thoracis (LT) and semitendinosus (ST) muscles were investigated in 21 Normand cull cows. Animals were assigned in a 100 d finishing period to straw (30%) and concentrate (70%) based (C) or the same diet supplemented with linseed (L) or with rapeseed (66%) plus linseed (33%) (RL). Beef polar and neutral lipids were purified by liquid chromatography and their FA analysed by GLC. Trans and cis 181, purified by HPLC from total FA methyl esters, were analysed by GLC-MS. L and LR diets did not increase beef lipid deposition, but had modified FA composition of both LT and ST muscles in favouring deposition of 183n-3 and 9cis,11tr 182 (CLA), mainly to the detriment of 181∆9 cis (neutral lipids) and 182n-6 (polar lipids). However, they did not favour deposition of LC n-3 PUFA in the two muscles, but had increased deposition of trans 181 significantly, especially of ∆13tr to ∆16tr isoforms to the detriment of ∆10tr 181 (L diet) and of ∆11tr 181 (RL diet).