Requirement of Red Sea Bream for Dietary Mg

Abstract

Red sea bream, Chrysophrys major, were fed diets with and without supplemental magnesium (66 and 12 mg Mg per 100 g diet, respectively) over a 60-day period. No significant differences were recognized between the two groups in the following determinations: the growth rate, feed efficiency, condition factor, and hepatosomatic index; the hemoglobin content, hematocrit value, red blood cell count, mean corpuscular hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin concentration, mean corpuscular diameter, percentage of immature erythrocytes, number of lymphocytes and granulocytes per 1000 red blood cells, and content of magnesium in the whole blood; the blood serum levels of calcium, inorganic phosphorus, and urea-N; the moisture, lipid, and glycogen content of the dorsal muscle and liver; and the ash, calcium, phosphorus, and magnesium content of the vertebrae. Furthermore, no pathological change was recognized in the organs, erythrocytes, and leucocytes of fish fed the diet without the magnesium supplement. From these findings, it appears that magnesium supplementation in the diet for red sea bream is not essential, when the magnesium exists at a level exceeding 12 mg per 100 g diet. © 1979, The Japanese Society of Fisheries Science. All rights reserved.