シオミズツボワムシBrachionus plicatilisの栄養価とω3高度不飽和酸〔種苗生産における栄養学的研究-7-〕

概要

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The relationship between the dietary value of rotifers, Brachionus plicatilis, and their content of ω3 highly unsaturated fatty acids (ω3HUFA), the essential fatty acids for red sea bream, was investigated by feeding them marine chlorella Chlorelta minurissima or freshwater chlarella Chlorelia regularis for 10 min to 7 days. When marine chlorelia was used as a culture medium, the quite low content of ω3 HUFA in rotifers cultured with baker's yeast, Saccharomyces cerevisiae (Y-rotifers), increased in proportion to the culture period by the incorporation of 20:5 ω3 from marine chlorella, and reached a maximum at 27% in a two-day feeding. Furthermore, the dietary value of Y-rotifers for red sea bream larvae was found to be significantly improved by the secondary culture with marine chlorella for more than 6 h. Y-rotifers cultured secondarily with freshwater dhlorella were high in the contents of 18:2ω6 and 18:3ω3, but low in the content ofω3 HUFA and their dietary value was not much improved. These results indicate that the contcnt of ω3 HUFA in the rotifers is the principal factor in the dietary value of rotifers as a living feed and that the high mortality observed frequently in red sea bream larvae induced by feeding them Y-rotifers as their sole feed is duo to an EFA deficiency in the fish.