[Effect of rapeseed in beef cattle feeding on fatty acid composition, vitamin E content and oxidative stability of body fat].

Four groups of five fattening bulls each consumed a concentrate--wheat straw-diet (2.5:1) supplemented with either 0, 7, 14 or 21% ground rape seed for 350 days. Rape seed contained 427 g crude fat (ether extract) and 127 mg vitamin E per kg dry matter. The supplementation with rapeseed increased the fat concentrations in the rations from 25 to 50, 75 and 100 g, and of vitamin E from 11 to 19, 26 and 34 mg per kg dry matter. All bulls were slaughtered with about 560 kg body weight. Fatty acid composition of depot fat and of the fat of musc. long. dorsi were determined by gas liquid chromatography. Vitamin E concentrations in blood, depot fat and muscle were determined by HPLC. Oxidative stability of depot fat was measured as induction time by means of rancimat-test. Rape seed supplementation decreased C16-fatty acids and increased C18-fatty acids in depot and muscle fat. Muscle fat contained significantly more mono and poly unsaturated fatty acids (40.2 and 7.4%) than depot fat (33.5 and 2.0%, respectively). Rape seed supplementation enhanced significantly the vitamin E-concentrations in all body samples. In depot fat vit. E increased from 4.5 to 7.3, 8.5 and 14.9 micrograms/g. Induction time increased from 10.9 to 18.5, 16.1 and 19.5 h, when 0, 7, 14 or 21% rapeseed were added.