Authors: MUSTAFA YILDIZ
Abstract: Lipid contents and fatty acid profiles in the commercial microdiets for farming marine fish species were determined. Twenty microdiet samples were taken from marine fish farms on the Aegean region of Turkey throughout 2006-2007. Of the 20 microdiet samples, 5 were produced in Turkey and 15 were imported. The fatty acid analysis of the microdiets was made by gas-liquid chromatography using helium as the carrier gas. The lipid levels of the microdiets produced in Turkey by different companies ranged from 9.5 ± 0.05% to 11.6 ± 0.14% (P < 0.05). In contrast, the lipid levels of imported microdiets were between 10.6 ± 0.20% and 17.2 ± 0.14% (P < 0.05). n-3 polyunsaturated fatty acids (n-3 PUFA) levels in the microdiets ranged from 7.1 ± 0.03% to 24.8 ± 0.03% of total fatty acids (P < 0.05). Similarly, n-3 highly unsaturated fatty acid (n-3 HUFA) levels in the microdiets ranged from 6.1 ± 0.01% to 22.8 ± 0.02% of total fatty acids (P < 0.05). n-3 highly unsaturated fatty acids (n-3 HUFA) levels in the microdiets were found between 0.6 ± 0.00% and 3.6 ± 0.01% of dry weight of diets (P < 0.05). Docosahexaenoic acid (DHA) levels of these microdiets were between 0.3 ± 0.00% and 2.0 ± 0.03% of the dry weight of diets (P < 0.05). Eicosapentaenoic acid (EPA) levels in the dry weight of diets were between 0.3 ± 0.01% and 2.2 ± 0.01% (P < 0.05). Arachidonic acid (ArA) levels in the microdiets were also found between 0.3 ± 0.01% and 0.9 ± 0.01% of total fatty acids (P < 0.05). The value of DHA/EPA ratios in the microdiets ranged from 0.5 ± 0.01 to 2.0 ± 0.01 (P > 0.05). The results showed that the total lipid or n-3 and n-6 HUFA percentages especially DHA, EPA, ArA levels, and DHA/EPA ratios in the microdiets covered essential fatty acid (EFA) needs for larvae or early juvenile sea bass and sea bream. However, microdiets 3 and 13 had a slightly lower ratio of n-3 HUFA levels required for larval or early juvenile of these species.
Keywords: Marine fish, commercial microdiets, fatty acid profile, n-3 EFA
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