Studies with rainbow trout (Salmo gairdneri, R.) on the optimum level of dietary protein and on the utilization of casein.

Two feeding trials with rainbow trout were conducted over 100 days. Replacement of krill meal by gelatinized maize starch had negative effects on feed conversion and growth only when dietary protein was reduced below 33 per cent of the dry matter. When casein was the only source of protein, poor conversion and growth rates resulted. In diets containing 30 per cent krill meal, however, replacing 200 g per kg of gelatinized maize starch by casein improved feed conversion and growth. Increasing dietary gelatinized maize starch correspondingly increased glycogen contents of the liver. Replacing krill protein by casein caused fatty livers.