An experiment was conducted to evaluate nutritional quality of several protein sources in diet for juvenile abalone Haliotis discus hannai INO by feeding them diets containing each of protein sources at a 30% level for 40 days. Growth rate expressed as a relative value to that obtained in the group receiving a diet containing casein as a protein source and PER of each protein source were measured as follows, casein: 100, 4.2; soybean meal: 63, 2.6; leaf protein concentrate prepared from rye grass: 53, 1.9; egg albumin: 47, 1.6; whole egg: 44, 1.6; white fishmeal: 35, 1.7 and corn gluten meal: 23, 1.2, respectively.
These values were the highest in the abalone fed with the casein diet, suggesting a high nutri-tional quality of casein as a protein source in diet for abalone. While the dietary value of egg albumin, whole egg and white fishmeal were far inferior to casein, being quite different from the case of fish. The difference in protein quality is postulated to be mainly due to difference of digestibility of each protein source in the juvenile abalone. Improvement of digestibility of white fishmeal will be required for development of practical abalone feeds.