Effects of inorganic and organic dietary copper supplementation on growth performance and tissue composition for juvenile red drum ( Sciaenops ocellatus L.)

Abstract

A feeding trial was conducted to evaluate the dietary copper requirement of red drum (Sciaenops ocellatus) and compare the bioavailability of copper sulphate (CuSO₄) and copper‐ethanolamine. A basal diet was formulated using semi‐purified ingredients and analysed to contain 3 mg Cu/kg. Both copper sources were supplemented to the basal diet at either 5, 10 or 20 mg Cu/kg of dry diet. No significant differences were observed in growth performance of fish fed the various diets. However, red drum fed all copper‐supplemented diets retained more copper in liver and whole‐body tissues compared to fish fed the basal diet. Within both inorganic and organic copper treatments, the highest tissue copper concentrations were observed in fish fed diets supplemented with 10 mg Cu/kg. No significant differences were detected in net copper retention regardless of the nature of the copper source; hence, the bioavailability of copper sulphate and copper‐ethanolamine complex was not different in the diets for juvenile red drum. Furthermore, the minimum copper requirement for growth performance of juvenile red drum appeared to be satisfied when fish were fed the basal diet containing 3 mg Cu/kg diet, and no detrimental effects were observed in red drum fed diets supplemented with 20 mg Cu/kg.