Protein Source for Fish Feed-III. Inclusion of Defatted Soybean Meal in Diet for Fingerling Yellotail.

A feeding trial was performed with the fingerling yellowtail Seriola quinqueradiata to evaluate several kinds of defatted soybean meal as a partial substitute for fish meal in the diet. Fish fed on diets including up to 20% commercially available defatted soybean meal showed just as good growth and feed efficiency as that fed on the control diet free from soybean meal and high in fish meal, while feeding with a 30% soybean meal diet appreciably depressed the performance. No marked differences were observed in the general composition of the fish body and the hematological characteristics among the groups, although the concentration of plasma zinc decreased as the soybean meal levels of the diets increased. Of the four kinds of soybean meal (commercial meal, severely heated meal, amino acid-supplemented meal, and purified meal), the best growth rate and feed efficiency were obtained from fish fed on the diet with purified meal. While a similar and an inferior performance was found in fish fed on the diet with amino acid-supplemented and severely heated meals, respectively, in comparison to that of the commercial meal group. These findings indicate that commercial defatted meal can substitute for fish meal in up to 20% of the diet for fingerling yellowtail, while purified soybean meal such as soy protein concentrate is a better protein source.