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

Three separate enrichment trials compared the n - 3 highly unsaturated fatt y 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 en richment dose (0.05, 0.1, 0.2, 0.3 and 0.4 g l(-1))and the degree of diluti on 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 emulsio ns were distributed by the International Council for the Exploration of the Seal Working Group on the Mass Rearing of Juvenile Fish (ICES). After the 48-h enrichment, the content of docosahexaenoic acid (DHA), eicosapentaenoi c acid (EPA) and total n - 3 HUFA increased to 23.1, 46.4 and 74.3 mg g(-1) DW, 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 HUF A). After the 12-h enrichment, the highest enrichment level of DHA, EPA and total n - 3 HUFA was observed at the 0.4 g l(-1) dose (12.7, 30.2 and 35.3 mg g(-1) DW, respectively). After the 24-h enrichment, the highest enrichm ent levels were, however, found at the 0.3 g l(-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 l(-1) dose. After 12 h enrichment, no significant differ ence in n - 3 HUFA levels was found among the 100/0, the 50/50 and the 25/7 5 treatments. After 24 h enrichment, the content of DHA in nauplii of the 1 00/0 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. (C) 2000 Elsevier Science B.V. All rights reserved.