Dietary value of rotifers and Artemia enriched with Euglena gracilis for red sea bream

Since Euglena gracilis incorporate and accumulate n-3 highly unsaturated fatty acids (n-3 HUFA), the fatty acid composition of the cells can be controlled by supplementation of the fatty acids into growth media. Rotifers and Artemia were enriched with Euglena that ac-cumulated docosahexaenoic acid (DHA). The DHA content of the rotifers fed on more than 100000 cells/ml of Euglena increased in 12 hours. Also, the feeding density of more than 100000 cells/ml gave an increase in the DHA content in Artemia. As for Artemia, however, DHA was degraded fast after 6 hours of enrichment. A feeding experiment was conducted to evaluate the dietary value of living feed enriched with Euglena. Rotifers and Artemia enriched with Euglena contained much more DHA than those enriched with Nannochloropsis or methyl esters of n-3 HUFA. The larval red sea bream fed on living feed containing more DHA showed higher activity in the activity test. Thus, the dietary value of rotifers and Artemia to red sea bream was effectively improved by enrichment with Euglena. Euglena is expected to be profitable feed for the DHA enrichment of rotifers and Artemia.