The influence of high dietary fat levels on protein utilization by the trout, (Salmo gairdnerii)

Abstract

• 1. The effect of total dietary energy content on protein utilization and on the levels of certain liver enzymes in trout was examined. Groups of trout or individual trout were fed a commercial diet to which different additional amounts of olive oil had been added.

• 2. Fat digestibility was not affected by fat content in the diet. Dietary lipid levels did not affect protein digestibility.

• 3. Indices of protein utilization improved markedly as dietary lipid level was increased. The effect was shown by an increase in biological value and a significant increase of protein productive value.

• 4. Glutamate-pyruvate transaminase activity decreased and glucose-6-phosphatase activity increased when trout were fed a high lipid diet.

• 5. The activities of other liver enzymes, (glutamate-oxaloacetate transaminase, lactic-dehydrogenase, glycerophosphate dehydrogenase and phosphoenolpyruvate carboxykinase) was neither increased nor decreased by dietary changes involving increases in fat level.