Influence of dietary fat on the fatty acid pattern of muscle and liver lipids in rainbow trout (Sabno gairdneri)

Groups of one year old rainbow trout (Salmo gairdneri) were fed diets supplemented with 13% of rape seed oil, olive oil, linseed oil or sunflower seed oil. The fishes were kept in fresh water of a temperature about 10°C throughout the 5 weeks experimental period. Random samples of fish were taken at 0, 1, 3 and 5 weeks, boneless filets taken from the back and livers were collected for analysis. The composition of the major fatty acids was determined in fats extracted from the diets and the samples of organs. The results showed the effect of the dietary fatty acids on the deposition in liver and filets. In all groups the major fatty acid of the supplemented fat increased in filets and livers already after one week. The increases continued during the feeding period for fat from the filets, whereas the livers showed the most pronounced increases after one week, followed by moderate increases or even a decrease after 3 and 5 weeks on the diets. There was a corresponding decrease in the percentage values for all other fatty acids except those which are synthesized from the dietary acids or from the metabolic pool. Linoleic and linolenic acids, which are polar (mobile) acids, increased more rapidly and to higher percentage values than the less polar monoene acids of chain length 20 and 22