Effect of dietary essential fatty acids on growth, body composition and blood chemistry of juvenile starry flounder (Platichthys stellatus)

A 10-week feeding experiment was conducted to investigate the effects of dietary lipid source and n-3 highly unsaturated fatty acids (n-3 HUFA) level on growth, body composition and blood chemistry of juvenile starry flounder. Three replicate groups of fish (average weight 1.9 g) were fed diets containing different n-3 HUFA levels ranging from 0.0% to 2.7% adjusted by either lauric acid as sole lipid source or different proportions of corn oil, linseed oil and squid liver oil at 10% of total lipid. Survival was not affected by dietary lipid source or n-3 HUFA level. Weight gain, feed efficiency and protein efficiency ratio of fish fed the diets containing squid liver oil were significantly higher than those fed the diets containing lauric acid, corn oil or linseed oil as the sole lipid source. However, there were no significant differences in weight gain, feed efficiency and protein efficiency ratio among fish fed the diets containing different n-3 HUFA levels ranging from 0.6% to 2.7%. Dietary n-3 HUFA requirement when using a broken line model was estimated at 0.9% for weight gain of fish. Crude lipid content of fish fed the diet containing lauric acid was significantly lower than that of other groups. Fatty acid compositions of neutral and polar lipid of fish were directly reflected by dietary fatty acid composition. The highest 14:0, 18:2n-6, 18:3n-3 and n-3 HUFA contents were observed in fish fed the diets containing lauric acid, corn oil, linseed oil and squid liver oil, respectively. The contents of n-3 HUFA in fish linearly increased with increasing dietary squid liver oil. Plasma cholesterol concentration and aspartate aminotransferase activity were affected by dietary lipid sources. These results indicate that dietary n-3 HUFA are essential and a value of at least 0.9% of n-3 HUFA in the diet could be recommended for optimum growth and efficient feed utilization of juvenile starry flounder. (C) 2003 Elsevier Science B.V. All rights reserved.