EFFECT OF DIETARY RATIOS OF DHA, epa and aa on early growth, survival and pigmentation of yellowtail flounder (pleuronectes ferrugineus)
L.A. Copeman, C.C. Parrish, J.A. Brown, M. Harel-1999
Bulletin of the Aquaculture Association of Canada,
99-4: 19-21
Abstract:
Marine fish require
the dietary polyunsaturated fatty acids (PUFA) docosahexaenoic acid (DHA,
22:6n-3), eicosapentaenoic acid (EPA, 20:5n-3) and arachidonic acid (AA,
20:4n-6) for normal growth and development. However, little is known about
the fatty acid requirements of yellowtail flounder (Pleuronectes
ferrugineus) larvae. Consequently, we designed an experiment to study the
role of dietary ratios of these fatty acids on their early growth, survival,
lipid composition, and pigmentation. Rotifers were enriched with emulsions
high in DHA (43.3% of total fatty acids), DHA+EPA (37.4% and 14.2%
respectively), DHA+AA (36.0% and 8.9% respectively), or with a control (no
DHA, EPA, or AA) emulsion. After four weeks, larvae fed the high DHA diet
were significantly larger (9.7 mm, P<0.05) and had higher survival (22%)
than larvae fed the other diets, while larvae on the control diet were
significantly smaller (7.3 mm, P<0.05) and showed lower survival (5%).
Larval lipid class and fatty acid profiles showed significant differences,
with fatty acids reflecting dietary levels. The incidence of malpigmentation
was higher in the high DHA+AA diet (92%) than in the other treatments
(<64%). We conclude that yellowtail larvae require diets that are highly
enriched with DHA, while elevated dietary AA may exert negative affects on
larval pigmentation.
(Ocean Science Centre, Memorial University of
Newfoundland, St. John’s, NF, Canada, A1C 5S7)