Changes of Mineral Compositions in Whole Body of Rainbow Trout during Growing Stages

Abstract

Changes in mineral composition at some defined stages of developing eggs of rainbow trout and after feeding swim up fry with diets with or without supplement of various trace metals for 40 weeks were determined. The contents of K, Mg and Na changed largely until 12th week after feeding, and then became constant. Levels of Ca and P reached almost plateau at the stage of 20 weeks after swim up, which was 8 weeks later than those of K, Na, Mg and Fe. Concentrations of Ca and P in whole body were affected by available Zn levels in diets. Contents of Zn and Mn in whole body also changed significantly in each experimental group during 12 weeks feeding, being affected by deletion of these metals from the mineral mixture in diets. The results of this study have demonstrated that the mineral composition in whole body of rainbow trout changed markedly over the 12 weeks period from swim up fry to fingerlings, especially after receiving diets, and then became stable between 12th and 40th week. © 1987, The Japanese Society of Fisheries Science. All rights reserved.