CHRONIC DIETARY EXPOSURE TO COPPER AFFECTS GROWTH, TISSUE LIPID-PEROXIDATION, AND METAL COMPOSITION OF THE GREY MULLET, CHELON LABROSUS

Juvenile grey muller (Chelon labrosus) were fed either a basal (4.4mg Cu/kg dry wt) or high-Cu diet (2400 mg Cu metal/kg dry wt) for IO week s to assess the relationship between growth and Cu-induced oxidative d amage. No mortalities were observed, but growth rate and food intake w ere reduced by 43 and 29%, respectively, in the high-Cu group. This wa s not only attributed to peroxidative damage of the food which reduced food intake (palatability), but also to direct effects of hepatic lip id peroxidation. Hepatic a-tocopherol concentrations were 63% lower, w hile malondialdehyde (MDA) increased by 304% in mullet fed a high-Cu d iet far 67 d. Cu-exposure reduced apparent alpha-tocopherol retention by 420%. Hepatic Fe and Zn levels fell, while Cu increased (p < 0.05). The results show that oral Cu exposure induces oxidative stress in gr ey mullet. Quantification of lipid peroxidation (rancidity) in the foo d, reflecting palatability, is essential to differentiate the direct t oxic effects of Cu on growth from the secondary influences of reduced food intake. (C) 1998 Elsevier Science Ltd. All rights reserved.