| Popis: |
The study was conducted to elucidate the value of the free fatty acid (ffa) level as a criterion of quality of fats and oils in diets for salmonid fishes. Capelin oils with varying contents of ffa (0.1–11.0%) were fed to rainbow trout (Salmo gairdneri, Richardson) fingerlings in one experiment and to salmon parr (Salmo salar, L.) in another experiment. Fish growth was good on all experimental diets in both experiments. The level of ffa had no significant effect on fish growth. For rainbow trout the mortality was somewhat greater on the diet with the lower (1.8%) than on that with the higher (11.0%) ffa content, but for salmon parr there was no clear relationship between the mortality and the level of ffa in the fish oil. For the chemical composition of the carcasses and the carcass traits the only significant difference was that there was slightly more fat in the body of the fish fed fat with a low content of ffa. The digestibility of protein, fat and the gross energy in the diet did not seem to be influenced by the ffa content in the diet. It is concluded that the dietary content of free fatty acids as the sole criterion gives no indication of the value of the fat as a feed ingredient for salmonids. |
