Vitamin A metabolism and
early biological responses in juvenile sunshine bass (Morone chrysops×M.
saxatilis) fed graded levels of vitamin A
G.-I. Hemre, D.-F. Deng, R.P. Wilson, M.H.G.
Berntssen-2004
Aquaculture, 235(1-4): 645-658
Abstract:
The present study evaluated the effects of increasing
levels of dietary retinol on diet utilisation, growth, mortality, retention
of vitamin A1 plus its conversion to vitamin A2 in
liver and whole body of juvenile sunshine bass. In addition, early
indications of disturbed intestinal cell kinetics, as well as liver
heat-shock protein 70 (HSP70) responses were included. Feeding juvenile
sunshine bass a purified, casein-based diet with no added retinol resulted
in significantly lower growth. Feeding diets containing from 509 to 40 516
µg retinol kg−1 resulted in equal growth, survival, feed
efficiency, condition factors as well as liver and carcass indices. However,
dietary retinol levels were reflected in both liver and whole body in a
linear manner, but with no retention in the groups fed a deficient or 509 µg
retinol kg−1 diet. The conversion of vitamins A1
to A2 in all groups depended on the dietary level of vitamin A1.
Fish fed the 40 516 µg retinol kg−1 diet had reduced
conversion of vitamins A1 to A2 and altered
distribution of proliferating cell nuclear antigen (PCNA)-positive cells
along their intestinal folds and crypts. The resistance to temperature
stress and expression of liver HSP70 appeared to be efficient in all dietary
treatments, but fish fed the 1614 µg retinol kg−1 diet
showed the greatest increase in HSP70 following heat shock, compared to the
other groups. Based on growth, mortality, retention and conversion of
vitamins A1 and A2, distribution of PCNA-positive
cells and increase in HSP70, we conclude that the requirement for optimal
growth and health of sunshine bass is greater than 509 µg retinol kg−1
diet and less than 40,516 µg retinol kg−1 diet.
(NIFES, National Institute of Nutrition and Seafood
Research, P.O. Box 176, Sentrum, N-5804, Bergen, Norway, e-mail: gro-ingunn.hemre@nifes.no)