Changes with different diets in plasma enzymes (GOT, GPT, LDH, ALP) and plasma lipids (cholesterol, triglycerides) of sea-bass ( Dicentrarchus labrax)

Abstract

Artificial diets presently available for sea-bass ( Dicentrarchus labrax) do not totally ensure good physiological conditions. Two diets, one with polyunsaturated fatty acids (PUFA) and one without, were tested on two lots of fishes for 5 months. GPC analysis of polyunsaturated fatty acids in both diets showed the presence of docosahexaenoic acid (essential fatty acid for marine fishes) in the first diet. Serum levels of cholesterol and triglycerides corresponding to the two diets were significantly different, with higher values for the diet without docosahexaenoic acid, and for this diet enzymatic activities showed significantly higher values for alkaline phosphatase (ALP) and glutamic-oxaloacetic acid transaminase (GOT). On the other hand, no significant difference could be found between the diets for lactic dehydrogenase (LDH) and glutamic-pyruvic acid transaminase (GPT) levels in the serum. Histologically, the hepatic parenchyma was seen to develop into a generalized massive steatosis, exhibiting necrotic centers and fat pseudocysts with the docosahexaenoic acid-free diet. With the docosahexaenoic acid diet, although a macrovacuolar steatosis was observed, a proliferation of bile ducts and signs of ductal regression pointing to a regenerative process could be seen. The significant results obtained and the correlations between biochemical parameters and histopathological investigations show how important it is to use serum tests in fish farming. The diagnosis of healthy liver should allow optimized diets to be devised for a given species.