Liver ornithine decarboxylase activity in the European sea bass (Dicentrarchus labrax L.): effects of protein composition of the diet, environmental conditions and age

Abstract 1. 1. European sea bass of one or two years of age kept for ten weeks at a water temperature of 22–26°C, exhibited significantly higher hepatic ornithine decarboxylase activity when fed on a diet containing 70% herring meal than diets where the latter was partially replaced by isolated soybean meal protein or casein. 2. 2. This was reversed in animals maintained six more weeks under the same feeding regimen while the water temperature was decreasing down to 15°C. 3. 3. Statistical analysis showed that water physical conditions significantly interacted both with diet protein composition and age in affecting this enzymatic activity.