Lipids and fatty acids in Artemia nauplii enriched with fish oil triacylglycerols containing docosahexaenoic acid in different positional distribution patterns

Lipid profiles were compared between Artemia nauplii enriched with fish oh triacylglycerols (TG) containing docosahexaenoic acid (DHA, 22:6n-3) in different positional distribution patterns. Four fish oils were selected on the basis of the positional distribution determined by a nonenzymatic analytical method, and directly given to Artemia nauplii in the form of oil emulsions. Time-courses of the lipid contents, lipid compositions, and fatty acid compositions were not so different between the nauplii enriched with tuna orbital and bonito head oil TG, in which 22:6n-3 (22.9-24.0%) was esterified in the sn-3>sn-1 much greater than sn-2 positions and the sn-3 much greater than sn-2=sn-1 positions, respectively. In both of the enrichments, the level of 22:6n-3 initially not detected reached a plateau (3.4-3.6% of total fatty acids) after 12 h and then decreased to 1.7% (48 h). Slight differences were also observed between the lipids of nauplii fed on sardine (22:6n-3, 11.5%; sn-2 much greater than sn-3 > sn-1) and seal (22:6n-3, 7.6%; sn-3 > sn-1 > sn-2) oil TG. The levels of 22:6n-3 after 24 h enrichment were 0.4% of total fatty acids. Such similarities of the lipid profiles in Artemia nauplii indicate that the positional distribution of 22:6n-3 in dietary TG has practically no influence to enrichment of Artemia nauplii with this fatty acid. It is probable that any TG with different positional distribution patterns of 22:6n-3 can be used for enrichment of Artemia, when 22:6n-3 is concentrated in the TG at an adequate level.