The malt protein flour (MPF) used is a newly developed protein source from brewer's spent grain. MPF has lower protein and higher carbohydrate contents, as well as higher phenylalanine and lower lysine contents than fish meal. Its nutritive value and biological availability were evaluated by chemical analysis and feeding trials. Fingerling yellowtail Seriola quinqueradiata were fed with fish meal-based moist pellet diets containing 0-40% MPF in 0.8 ton aquaria 30 days. Dietary inclusion of MPF tended to depress the growth rate and feed efficiency as its level increased. The inclusion of more than 30% MPF significantly lowered these values and the body fat content and hematological characteristics, probably due to its poor digestibility and amino acid profile. However, dietary inclusion of less than 20% MPF resulted in a comparable growth performance and hematological characteristics to the MPF-free control diet. These results indicate that MPF is useful as an alternative protein source, and can substitute for fish meal up to 20% in the diet for fingerling yellowtail without any adverse effects.
