INFLUENCE OF OILSEEDS IN COMBINATION WITH VITAMIN-E SUPPLEMENTATION IN THE DIET ON BACKFAT QUALITY OF PIGS

To study combination effects of oilseeds and vitamin E supplements in the diet on backfat quality, two feeding experiments with a total of 6 0 growing-finishing pigs were designed. Experiment 1 (24 pigs) include d a control group with a cereal/soybean-meal diet and two experimental groups with 100 g kg(-1) rapeseed or 200 g kg(-1) full-fat soybeans, resulting in an increase of ether extract from 28 to 74 or 69 g kg(-1) respectively. Three weeks before slaughter, four animals of each grou p were fed additionally with 1 g alpha-tocopherol acetate per animal p er day, In experiment 2, four groups of nine pigs each received a cere al/soybean meal diet, and 0, 1, 2 and 3 weeks before slaughtering, the animals were given 1 g alpha-tocopherol acetate per day. Tocopherol c oncentration in blood, liver, muscle and backfat was determined by app lying the HPLC technique. In addition, the fatty acid pattern of the b ackfat was analyzed using capillary gas chromatography and the oxidati ve stability of the fat was determined using the Rancimat test. In exp eriment 1, oilseed influenced the fatty acid pattern of the backfat, T he percentage of linolic and linolenic acid increased significantly an d a tendency towards lower proportions of saturated fatty acids was de tected. However, the full-fat soybean diet decreased the percentage of oleic acid significantly. Vitamin E supplements three weeks before sl aughter increased vitamin E concentration of backfat from 12.3 to 31.1 mg kg(-1). The response to dietary alpha-tocopherol intake in the var ious organs was found to be in the sequence liver > subcutaneous fat > serum > muscle. Oxidative induction time of backfat varied between 2. 9 and 13.7 h depending on the fatty acid pattern and the vitamin E con centration. The shortest induction times were observed when oilseed wi thout vitamin E supplements were fed. The longest times were observed after feeding the soybean/cereal diet with vitamin E supplements. In e xperiment 2, vitamin E concentration of backfat was much lower (rangin g between 7.0 and 12.8 mg kg(-1)) than in experiment 1. Vitamin E admi nistration over three weeks doubled vitamin E concentration in backfat and also induction time. Results demonstrate the antioxidative effect s of vitamin E and its meat quality improving properties.