EFFECTS OF THE DELETION OF CA OR TRACE-ELEMENTS FROM SEMI-PURIFIED DIET ON GROWTH AND FEED-UTILIZATION OF YELLOW CROAKER, NIBEA-ALBIFLORA

This study was conducted to determine the effect of the deletion of Ca or trace elements from semi-purified diets on growth and body composi tion of the yellow croaker Nibea albiflora. Fish with mean average wei ght 28.8+/-2.5 g were fed on test diets with (control group) and witho ut supplement of Ca or trace elements for 14 weeks at 20.0-22.5 degree s C. No significant difference was observed in the growth of fish grou ps fed on diets deficient with Ca or trace elements and the control gr oup. No apparent effect of feeding diets without Ca or trace elements was detected in hematological characteristics in all test groups, Howe ver, serum contents of Ca and inorganic P were higher in fish group re ceived Ca deficient diet compared to the control. Bone contents of Mn, Cu and Zn decreased distinctly in fish group fed deficient trace elem ents diet. No obvious effect on the mineral contents of liver was seen in fish from all test groups. It appears from these findings that, Fo r growth performance, yellow croaker can met their requirements of Ca or trace elements by direct assimilation of these minerals from the su rrounding mater but for ideal bone mineralization the addition of trac e elements in diet seems to be necessary.