EFFECT OF IRON SUPPLEMENTS ON A SOY PROTEIN-CONCENTRATE DIET ON HEMATOLOGY OF YELLOWTAIL

A 42-day feeding trial was conducted with young yellowtails (163.6 g) for the purpose of improving undesirable hematological characteristics caused by feeding a soy protein concentrate (SPC) diet (moist type pe llet). Zero, 50, 100, 250, 500, and 1000 mg of iron proteinate (Fe-P; 10-13 %Fe) were respectively added per each 100 g of the SPC diet, con taining 20 g SPC, 45 g brown fish meal, and 166 mg Fe-P. A reference d iet of hundred grams contained 65 g of brown fish meal and 166 mg Fe-P and used as a control. Although no meaningful effects of dietary Fe-P supplements on growth performances and Fe accumulation in the liver a nd spleen were found in the dietary groups, significantly lower red bl ood corpuscle count, hematocrit value, hemoglobin concentration, and s erum Fe saturation rates were detected in fish fed a control diet with out the Fe-P supplementation. There were no marked differences in desi rable hematological characteristics and serum Fe saturation rates betw een groups fed diets with above 250 mg of supplemental Fe-P and the re ference diet. These results suggest that undesirable hematological cha racteristics in yellowtails fed the SPC diet could be improved by prep aring dietary Fe-P content, above 400 mg per 100 g of SPC diet.