DIGESTIBILITY OF DIETARY PROTEIN IN RAINBOW TROUT-I

Abstract

The digestibility of several dietary proteins in rainbow trout was determined by the indirect method using chromium oxide as an indicator. The diets used and their chemical compositions are presented in Table 1. As summarized in Tables 2 and 3, the proteins of raw meats such as frozen fish, beef liver and spleen showed the highest values, 91-97 per cent, in digestibility amoung the pro-teins tested. Following these proteins, those of white fish meal, a commercial diet for rain-bow trout culture and dried silk-worm pupa showed about 80 per cent in digestibility. Soy-bean meal, a fish meal and the other commercial meal diets tested were more inferior in the digestibility of protein, about 70 per cent or under that. The removal of the fatty component from dried silk-worm pupa by ether extraction had little influence on the digestibility of the protein.