Aharoni, Y., Agricultural Research Organization, Institute of Animal Sciences, Beef Science Unit, Newe Yaar, P.O. Box 1021, Ramat Yishay 30095, Israel
Orlov, A., Agricultural Research Organization, Institute of Animal Sciences, Beef Science Unit, Newe Yaar, P.O. Box 1021, Ramat Yishay 30095, Israel
Brosh, A., Agricultural Research Organization, Institute of Animal Sciences, Beef Science Unit, Newe Yaar, P.O. Box 1021, Ramat Yishay 30095, Israel
Granit, R., Agricultural Research Organization, Inst. Technol. Storage Agric. Prod., Department of Food Science, Israel
Kanner, J., Agricultural Research Organization, Inst. Technol. Storage Agric. Prod., Department of Food Science, Israel

An experiment was conducted to study effects of soybean oil supplementation of a high forage fattening diet on the composition of fatty acids (FA), including vaccenic acid (VA) and conjugated linoleic acid (CLA), in lipid depots of the meat. Eighteen Friesian bull calves were fed a common total mixed ration, supplemented with either ground maize and soybean meal (C, control treatment) for a group of six calves, or soybean meal and soybean oil (SBO treatment) for a second six calf group, or extruded full fat soybean (FFS treatment) for a third six calf group. All the diets were calculated to be iso-nitrogenous and of the same ME content, and the amounts of fat added to the two oil-supplemented diets were also equal, at 33 g/kg of diet DM. The experiment commenced when the calves were 210 ± 3 days of age, weighing 290 ± 6 kg and lasted for 5 months until slaughter at a live weight of 470 ± 14 kg. Blood of the calves was sampled one week before slaughter for vitamin E determination in red blood cells. Slices of the longissimus muscle between the 12th and 13th ribs were sampled from all calves at slaughter and analysed for fatty acid composition of intra-muscular and subcutaneous fat. The CLA concentrations in the FAs in intramuscular fat were 3.4, 13.0 and 15.4 mg/g in the C, SBO and FFS treatments, respectively, and the corresponding CLA concentrations in the FAs in subcutaneous fat were 5.2, 20.3 and 26.6 mg/g, respectively. The concentrations of VA in both lipid depots were also about three times greater in the SBO and FFS treatments than in the C treatment. The response of increased CLA and VA in lipid depots of meat to oil supplementation was greater than that reported in previous studies, and the reasons for this finding are discussed. The vitamin E concentration in the blood tended to increase as a result of oil supplementation, despite the increased supplementation of poly-unsaturated fatty acids, which are sensitive to oxidation. © 2005 Elsevier B.V. All rights reserved.