Isomeric distribution of conjugated linoleic acids (CLA) in the tissues of layer hens fed a CLA diet

The isomeric distribution of conjugated linoleic acids (CLA) in the tissue lipids of hens in relation to that in the diet was examined. Silver-ion high-performance liquid chromatography was used to quantify individual CLA isomers in total tissue lipids, phospholipids, and triacylglycerols. It was found that the deposition of CLA isomers in hen tissues was selective. All tissues including serum, liver, heart, kidney, abdominal fat, and leg and breast muscles had lesser amounts of total cis/trans isomers ranging from 75.87 to 89.13% of total CLA, which was in contrast to the value of 92% of total CLA in the dietary lipids. Total trans/trans isomers in all tissue lipids ranging from 6.11 to 18.02% of total CLA were greater than that in the diet (4.19%). Among the individual trans/trans isomers, all tissues except for adipose tissue and brain incorporated greater amounts of t-12,t-14-18:2, t-11,t-13-18:2, t-10,t-12-18:2, t-9,t-11-18:2, and t-18,t-10-18:2 compared with the values of the diet. Within the cis/trans group, lesser amounts of c-10,t-12/t-110,c-12-18:2 were found to incorporate into all tissues compared with the value of the diet. Serum and liver had higher percentages of c-9,t-11/t-9,c-11, whereas the other tissues had similar levels of this isomer compared with that of the diet. It was also observed that supplementation of CLA in the diet of layer hens decreased the concentration of docosahexaenoic acid (22:6n-3) in all of the tissue lipids. It is concluded that dietary CLA can transfer to the tissue but that incorporation of CLA isomers into the tissue is selective in hens.