Effect of dietary supplementation with either conjugated linoleic acid (CLA) or linoleic acid rich oil on the CLA content of lamb tissues

Conjugated linoleic acid (CLA) is produced in the rumen by isomerization of linoleic acid and has been shown to be a potent anticarcinogen in animal model studies. The objective of this study was to compare the relative increase in the CLA content of lamb tissues by dietary CLA supplementation (0.33 g/d for 21 days prior to weaning) to milk-replacer of preruminant lambs or by feeding linoleic acid rich oil (Safflower oil, 6% DM-SAFF) to weaned ruminating lambs with that of lambs receiving unsupplemented milk-replacer and pelleted feed. Thirteen lambs were randomized to three dietary treatments (CLA-4, SAFF-4 and Control-5) and fed the pelleted diet for 80 days after weaning. Lambs were slaughtered at an average weight of 45 kg and tissue samples were procured from pars costalis diaphragmatis, leg, rib, subcutaneous adipose and liver for determination of fat and CLA content and fatty acid composition. Dietary supplementation with safflower oil increased fat content of subcutaneous adipose tissue only, but the CLA content of all the tissues was increased (P < 0.05) by more than 200%. Dietary safflower oil increased (P < 0.05) C18:2 in all tissues and C16:0 in the diaphragm, and decreased (P < 0.05) C18:1 and C18:3 content in all tissues. Supplementation of the diet with pre-formed CLA prior to weaning decreased (P < 0.05) fat content of the adipose tissue with decreases occurring in C18:0 relative to animals receiving the unsupplemented diet, however, tissue CLA content was not affected by provision of dietary CLA to pre-ruminant lambs, Results indicated that supplementation of lamb feedlot diets with a source of linoleic acid was a successful method of increasing CLA content of tissues. Crown copyright (C) 2000 Published by Elsevier Science B.V. All rights reserved.