Enrichment strategies for <i>Artemia</i> using emulsions providing different levels of n-3 highly unsaturated fatty acids

Three separate enrichment trials compared the n-3 highly unsaturated fatty acid (HUFA) levels in Artemia franciscana nauplii (Great Salt Lake, USA) as a function of the n-3 HUFA level in the emulsion (30% and 50%), the enrichment dose (0.05, 0.1, 0.2, 0.3 and 0.4 g1-1) and the degree of dilution of a high HUFA emulsion with an n -3 HUFA-free emulsion (100/0, 50/50, 25/75, 12.5/87.5 and 0/100, HUFA-rich/HUFA-free, w/w). The standard emulsions were distributed by the International Council for the Exploration of the Sea, Working Group on the Mass Rearing of Juvenile Fish (ICES). After the 48-h enrichment, the content of docosahexaenoic acid (DHA), eicosapentaenoic acid EPA) and total n-3 HUFA increased to 23.1, 46.4, and 74.3 mg g-1DW, respectively, in Artemia enriched with ICES 50 (50% n-3 HUFA) and to 14, 41.4, 59.9 mg g-1 DW in nauplii enriched with ICES 30 (30% n-3 HUFA). After the 12-h enrichment, the highest enrichment level of DHA, EPA and total n-3 HUFA was observed at the 0.4 g 1-1 dose (12.7, 30.2 and 45.3 mg g-1 DW, respectively) After the 24-h enrichment, the highest enrichment levels were, however, found at the 0.3 g1-1 dose, i.e., respectively, 28.9, 53.2 and 85.6 mg g-1 DW as compared to 21.7, 51.1, and 75.9 mg g-1 DW at the 0.4 g 1-1 dose. After 12 h enrichment, no significant difference in n-3 HUFA levels was found among the 100/0, the 50/50 and the 25/75 treatments. After 24 h enrichment, the content of DHA in nauplii of the 100/0 treatment was twice that of the 50/50 treatment (20.2 vs. 9.3 mg g-1 DW), which was in turn five times higher than in the 12.5/87.5 treatment