EFFECTS OF MILK-FAT, UNHYDROGENATED AND PARTIALLY HYDROGENATED VEGETABLE-OILS ON FAT-METABOLISM OF GROWING PIGS .1. GROWTH, FEED-UTILIZATION AND CARCASS QUALITY IN PIGS FED DIFFERENT FATS AND OILS

Two trials were conducted to study the effects of different dietary fa ts on the performance, carcass quality and meat quality of 75 crossbre d growing pigs. The experimental diets contained 14.3% butter oil (BO) , low erucic acid rapeseed oil (RO), sunflower oil (SO) or partially h ydrogenated sunflower oil (HSO). The cream (CR) content of the diets w as 29.4%. The dietary fat addition comprised about 36% of the net ener gy content of the diets. The fatty acid composition of the dietary fat s had a clear influence on the fatty acid composition of the adipose t issue of the pigs. Vegetable oils (RO and SO) increased the unsaturate d fatty acid content of the adipose tissue and decreased the firmness of the backfat compared to the effects by milk fat (BO, CR) (p<0.001). The correlation between linoleic acid content and firmness of back fa t was significant (r=-0.83) (p<0.001). The trans fatty acid (C18:1) fo und in HSO seems to be incorporated intact into the fatty tissue of th e pig to a large extent and a significant difference was found in the contents of trans fatty acid C18:1 between the SO and HSO treatments ( P<0.00 1). Significant differences were found in feed conversion effic iency, kg DM/kg gain, (p<0.05) and in the firmness of back fat (p<0.00 1) between the present vegetable oils (RO, SO, HSO) and the milk fat ( BO, CR) dietary groups. Hydrogenated sunflower oil (HSO) increased the firmness of back fat compared to unhydrogenated sunflower oil (SO) (p <0.001), but in contrast, it significantly reduced daily gain and feed conversion efficiency (p<0.05). A vegetable oil addition of the level used in the present study is not recomended for pig diets because of the undesirable consistency of back fat.