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Requirement of dietary n-3 highly unsaturated fatty acids for juvenile flounder (Paralichthys olivaceus)

Kim, K.D., Lee, S.M.
Aquaculture 2004 v.229 no.1-4 pp. 315-323
dietary fat, fatty acid composition, juveniles, farmed fish, essential fatty acids, Paralichthys olivaceus, feed conversion, flounder, nutrient requirements, feed composition, fish culture, lipid content, weight gain, animal growth, docosahexaenoic acid, eicosapentaenoic acid, body composition, protein intake, South Korea
The effect of dietary n-3 highly unsaturated fatty acids (n-3 HUFA) level on growth and body composition was investigated to determine the n-3 HUFA requirement for juvenile flounder. Eight diets of different n-3 HUFA levels ranging from 0.0% to 2.4% were fed to juvenile flounder for 8 weeks. For varying n-3 HUFA level, mixtures of mainly EPA (0.0-1.1%) and DHA (0.0-0.9%) were used except one diet containing only 1.2% EPA. Weight gain, feed efficiency and protein efficiency ratio increased significantly with increasing dietary n-3 HUFA level up to 0.8%; however, those values gradually decreased after n-3 HUFA level became higher than 1.6%. The result of second-order polynomial regression showed that the maximum weight gain could be attained at 1.0% n-3 HUFA level. The weight gain was significantly lower for the diet containing 1.2% EPA than for the 1.2% n-3 HUFA diet containing both EPA and DHA. The contents of DHA and n-3 HUFA in whole body polar lipid increased with dietary n-3 HUFA level. Monoenoic fatty acids content and 18:1n/n-3 HUFA ratio decreased with increasing dietary n-3 HUFA level. The results suggest that the requirement of dietary n-3 HUFA for juvenile flounder is about 0.8-1.0%; however, excessive n-3 HUFA supplement may impair the growth of juvenile flounder.