Essentiality of dietary n-3
highly unsaturated fatty acids in juvenile Japanese flounder Paralichthys
olivaceus
K.D. Kim, S.M. Lee, H.G. Park, S.C.C. Bai, Y.H.
Lee-2002
Journal of the World Aquaculture Society, 33(4):
432-440 (from ISI Current
Contents)
Abstract:
This study was conducted to confirm the essentiality of dietary n-3 highly
unsaturated fatty acids (n-3 HUFA) and to investigate the effects of dietary
lipid sources on growth performance, liver, and blood chemistry in juvenile
Japanese flounder. Three replicate groups of fish (average weighing 3.0 g)
were fed experimental diets containing lauric acid ethyl ester, soybean oil,
soybean and linseed oils mixture, and squid liver oil as lipid sources for
13 wk. No significant difference was observed in survival among all groups
(P > 0.05). Weight gain, feed efficiency and protein efficiency ratio of
fish fed the squid liver oil diet containing high n-3 HUFA level were
significantly higher than those of fish fed the other diets (P < 0.05).
Saturated and monounsaturated fatty acids of liver polar and neutral lipid
fractions in fish fed the diet containing lauric acid tended to increase
compared to those of the other groups. Fish fed the diets containing soybean
and/or linseed oils, which contained high contents of 18:2n-6 and 18:3n-3,
respectively, showed the highest contents of 18:2n-6 and 18:3n-3 in both
lipid fractions of the liver (P < 0.05). Significantly higher content of
n-3 HUFA was observed in both lipid fractions of the liver from fish fed the
diet containing squid liver oil than for fish fed the other diets (P <
0.05). Total cholesterol, glucose, and glutamic-oxaloacetic acid
transaminase in plasma were significantly affected by dietary lipids (P <
0.05). Histologically, the liver of fish fed the diet containing squid liver
oil had a clear distinction between nuclear and cytoplasm membranes;
however, cytoplasm of fish fed the diets containing lauric acid and soybean
oil was shrunken, and the hepatic cell outline was indistinguishable. It is
concluded that the dietary n-3 HUFA is essential for normal growth, and that
the dietary lipid sources affect growth performance, liver cell property,
and blood chemistry in juvenile Japanese flounder.
(Kangnung
Natl. Univ. Fac. Marine Biosci. & Technol., Gangneung 210702, South
Korea)