STUDIES ON THE NUTRITIONAL VALUE OF DEFATTED FISH FLOUR

In studies on the nutritional value of defatted fish flour, groups of male weanling rats were given otherwise adequate diets containing 7%, 10%, or 15% protein supplied by fish flour or casein. After 4 weeks, protein efficiency ratio (P.E.R.) values found for 7% and 10% fish flour were significantly higher than those for comparable levels of casein, but similar values were found for both proteins at the 15% level. The kidneys of the animals given diets containing 15% protein were significantly heavier than those of the animals fed the other diets, but level or source of dietary protein had no significant effects on liver and adrenal weights, or liver lipid levels.In further studies, fish flour was added to whole wheat flour or to white bread prior to baking, and the resulting mixtures were fed to growing male rats at the 10% protein level. Addition of 2, 4, or 6 lb of fish flour per 100 lb of whole wheat flour increased the P.E.R., in a stepwise manner, from 1.49 to 2.80 but had no effect on organ weights or liver lipid levels. Addition of 10% fish flour to white bread made with or without 4.2% milk solids increased the P.E.R. values by 82%, and 198% respectively, and significantly decreased liver lipid levels. The P.E.R. values for bread and flour diets were found to be a direct function of the lysine content of the protein.It was concluded that defatted fish flour is an excellent source of high quality protein, and should be of particular value in supplementing diets deficient in lysine.