[Addition of various types of fat to mixed dry feed as influencing the growth rate and the level of food utilization in rainbow trout (salmo gairdneri)].

Commercially prepared mixtures of dry feed for trout were supplemented with sunflower oil, cod liver oil or emulsions of fish oil in amount of about 5% and were fed to hatchery rainbow trout (Salmo gairdneri) for an experimental period of 112 days at water temperatures ranging from 13 degrees to 20 degrees C. The fish receiving the fatted pellets were clearly superior to the controls in regard of rate of gain, food utilization and protein utilization. The best results were obtained with additions of sunflower oil. In this case, the rate of gain was 382% as compared with 262% (for the controls), food consumption per weight gain of fish was 1.28 compared with 1.98, PER 2.04 compared with 1.26 and PPW (productive protein value) 34.5 relative to 22.4. Additions of fat to the feed increased the fat content of the experimental fish by about 3%, raising it to an average total of 11.5%. The same effect had already been observed in a previous trial as a result of a 10% addition of sunflower oil.