Effects of
dietary vitamin E on antioxidant defence mechanisms of juvenile turbot (Scophthalmus
maximus L.), halibut (Hippoglossus hippoglossus L.) and sea bream
(Sparus aurata L.)
D.R. Tocher, G. Mourente, A. Van Der Eecken, J.O. Evjemo, E. Diaz, J.G.
Bell, I. Geurden, P. Lavens, Y. Olsen-2002
Aquaculture
Nutrition, 8(3): 195-208
Abstract:
In order to enhance growth, survival and
quality during early juvenile stages of marine fish it is important to avoid
lipid oxidation problems that are known to cause pathologies and disease.
The aim of the present study was to characterize and compare the antioxidant
systems in juvenile marine fish of commercial importance in European
aquaculture, namely turbot (Scophthalmus maximus), halibut (Hippoglossus
hippoglossus) and gilthead sea bream (Sparus aurata). The
experiment investigated the interaction of the dietary antioxidant
micronutrient, vitamin E, with antioxidant defence systems. Fish were fed
with diets of identical unsaturation index supplemented with graded amounts
of vitamin E. The relationships between dietary and subsequent tissue
vitamin E levels were determined as well as the effects of vitamin E
supplementation on lipid and fatty acid compositions of both liver and whole
fish, on the activities of the liver antioxidant defence enzymes, and on the
levels of liver and whole body lipid peroxidation products, malondialdehyde
(thiobarbituric acid reactive substances, TBARS) and isoprostanes. Growth
and survival was only significantly affected in sea bream where feeding the
diet with the lowest vitamin E resulted in decreased survival and growth. A
gradation was observed in tissue vitamin E and polyunsaturated fatty acid
(PUFA)/vitamin E levels in response to dietary vitamin E levels in all
species. The activities of the main radical scavenging enzymes in the liver,
catalase, superoxide dismutase and glutathione peroxidase generally
reflected dietary and tissue vitamin E levels being highest in fish fed with
the lowest level of vitamin E. The indicators of lipid peroxidation gave
consistent results in all three species, generally being highest in fish fed
with the unsupplemented diet and generally lowest in fish fed with the diet
with highest vitamin E. In this respect, isoprostane levels generally
paralleled TBARS levels supporting their value as indicators of oxidative
stress in fish. Overall the relationships observed were logical in that
decreased dietary vitamin E led to decreased levels of tissue vitamin E, and
generally higher activities of the liver antioxidant enzymes and higher
levels of lipid peroxides.
(Institute of Aquaculture, University of Stirling,
Stirling, UK)