Apparent lipid and fatty acid digestion, retention of lipid and growth performance in Caspian salmon (Salmo trutta caspius) fry fed dietary n-3 highly unsaturated fatty acids and vitamin E

A 10-week feeding experiment was conducted to investigate the effect of dietary n-3 highly unsaturated fatty acids (n-3 HUFA) and vitamin E interaction on growth, apparent digestibility, apparent retention and utilization of lipid in Caspian salmon fry. Six experimental diets combining three different dietary levels of n-3 HUFAs (L: low: 1+0.5, DHA+EPA, M: medium 2+1, DHA+EPA, H: high 4+2 DHA +EPA g/100g diet) with two different levels of vitamin E (L: low 300 and H: high 1000 mg/kg diet): LL, LH, ML, MH, HL and HH (HUFA/vitamin E) were investigated. Fry with initial mean (±SD) body weight of 600 ± 25 (mg) were randomly distributed in tanks and fed to apparent satiation. Increase in dietary HUFA and vitamin E markedly improved larval growth. The results showed that the survival of Caspian salmon fry was not affected by dietary omega-3 HUFA and vitamin E. C20:5n-3 and C22:6n-3 fatty acids content of polar and neutral lipids positively correlated with their concentration on diets. Apparent digestibility and apparent retention of total lipid was significantly affected by dietary HUFA. The results showed that n-3 highly unsaturated fatty acids and vitamin E had positive effects on growth performance, lipid metabolism and apparent digestibility of Caspian salmon fry.