抄録
Little is known about the digestibilities of nutrients in marine invertebrates. In the present studies, the digestibilities of several proteins and carbohydrates in japanese top shell, Turbo cornutus, a seaweed feeder, have been determined by the chromic oxide indicator method.3) The composition of the synthetic diets used was shown in Table 1. The method of preparing diets was the same that applied in Haliotis (this bull., 29, 691 (1963)), namely, sodium alginate in the diets was converted to insoluble calcium alginate by dipping in CaCl2 solution and the nutrients were kept in it. The shells were provided with the film-shaped diets thus prepared. The chemical composition of the diets showed little change in sea water for several hours (Table 2). As shown in Table 3, casein was found to be the highest in digestibility among proteins tested, and followed by soybean meal-and dried brown algaproteins. The digestibilities of fish meal-proteins were low, especially in brown fish meal. The polysaccharides such as dextrin and alginic acid were considerably high in digestibility regardless the composition of the diet and laminarin showed also high value, whereas that of raw starch was low. The results obtained may be connected with the feeding habits of japanese top shell in nature.
