Growth, Tissue Lipid Peroxidation and Hepatic Trace Element Content of Soft-shelled Turtles, Pelodiscus sinensis, Fed a Cu-loaded Diet Followed by a Normal Diet

We investigated the responses of the soft-shelled turtle, Pelodiscus sinensis, to an optimal Cu diet following a 16-week exposure to a high-Cu diet. Juvenile soft-shelled turtles were fed a diet containing 158 mg Cu kg^(-1) for 16 weeks. After this feeding period, turtles were fed either the original diet or an optimal Cu diet (5 mg kg^(-1)) for 4 weeks. The weight gain of the turtles fed 5.0 mg Cu kg^(-1) was about 50% higher than that of the turtles fed 158 mg Cu kg^(-1). The liver Cu content of the turtles fed low-Cu diet (5.0 mg Cu kg^(-1)) was significantly (p＜0.05) lower than that of the turtles fed a Cu-loaded diet (158 mg Cu kg^(-1)). In contrast, the liver Fe content of the turtles fed a low-Cu diet was significantly (p＜0.05) higher than that of the turtles fed the high-Cu diet. Lipid peroxidation, assessed by thiobarbituric acid-reactive substances in the muscle lipids of the turtles fed diets containing 158 mg Cu kg^(-1), was significantly higher (p＜0.05) than that of the turtles fed a diet containing 5 mg Cu kg^(-1). Soft-shelled turtles are capable of removing the excessive Cu from their tissues after exposure to high dietary Cu when an optimal Cu diet is subsequently provided.