Growth and fatty acid composition of
freshwater prawn, Macrobrachium rosenbergii, larvae fed diets
containing various ratios of cod liver oil-corn oil mixture
M.S. Kamarudin, P. Roustaian-2002
Journal
of Applied Ichthyology, 18(3):
148-153
Abstract:
A feeding trial was conducted to determine the effect of replacing
costly cod liver oil with corn oil as a source of dietary lipid on the
growth and fatty acid composition of the larval freshwater prawn, Macrobrachium
rosenbergii de Man. Prawn larvae were weaned to artificial diets
containing cod liver oil and corn oil either singly or in various
combinations (2 : 1, 1 : 1, 1 : 2, w/w). Weaning to artificial diets from Artemia
nauplii commenced at larval stage III with complete substitution by
stage X. The reference group was reared solely on Artemia nauplii
during the entire experiment. Incorporation of corn oil at 33-67% of dietary
supplemental oil did not have significant effects on the post-larval
production. However, larvae fed with corn oil alone revealed a significantly
lower post-larval production compared to other experimental diets as well as
to the reference group. No significant differences (P > 0.05) were
observed in dry weight, protein and lipid concentration among larvae fed on
various dietary treatments. Palmitic (16 : 0) and oleic/vaccenic (18 : 1)
acids were the dominant saturated and monounsaturated fatty acids in larval
tissues, respectively, whereas the polyunsaturated fraction was dominated by
eicosapentaenoic (20 : 5n-3) acid. The polyunsaturated fatty acid
composition was dominated by n-3 acids rather than n-6 fatty acids. The
fatty acid composition of the prawn in general reflected that of the diet.
Larvae on diets containing higher concentrations of corn oil rich in
linoleic (18 : 2n-6) acid showed a higher concentration of this acid in
their tissues. No evidence of de novo synthesis of linoleic (18 :
2n-6) acid was found. Higher levels of stearic (18 : 0), arachidonic (20 :
4n-6) and eicosapentaenoic (20 : 5n-3) acids found in larvae as compared
with those fed Artemia and artificial diets strongly indicated the
larval ability in chain elongation and desaturation of palmitic (16 : 0),
linoleic (18 : 2n-6) or linolenic (18 : 3n-3) acids, respectively. Despite a
large variation of n-3 to n-6 ratios of the live and artificial diets,
larval n-3 to n-6 ratios were relatively stable among different dietary
treatments, possibly indicative of the importance of such a ratio in the
larval fatty acid metabolism.
(Aquatic
Biotechnology Laboratory, Department of Agrotechnology, Faculty of
Agriculture, Universiti Putra Malaysia, Serdang, Selangor, Malaysia)