Two different rotifer dietswere prepared (Table 1). Brachionus-High
was prepared as described above with Marol E added continuously
along with the other feed components, representing the standard rotifer
diet of the laboratory (control). The rotifer culture becomes
enriched by the n−3 highly unsaturated fatty acids (HUFA) of the
emulsion during normal growth, and the biochemical composition becomes
constantwith time. This method has been termed long-term enrichment
or combined growth and enrichment (Olsen, 2004; Olsen
et al., 1993; Rainuzzo et al., 1994b), and is well suited for use at low
temperature. Brachionus-Low was grown without a continuous addition
of Marol E, but was instead short-term enriched by this emulsion
for 2 h just before its use as live feed (Table 1). The ration of Marol E
given and the incubation time were adapted to yield a similar enrichment
of total lipids and n−3 HUFA, particularly DHA, for the two rotifer
diets. The rotifer cultureswere carefully rinsed by exchanging thewater
before their use for first feeding.