種苗生産における栄養学的研究 Ｘ マダイし魚に対する油脂酵母ワムシのじ料効果

Abstract

A new kind of yeast(ω-Yeast) as a food for rotifers was produced by supplementing pollock liver oil or cuttlefish liver oil at levels of 8% to 15% to the culture medium of baker's yeast Saccharomyces cerevisiae. The dietary value for red sea bream larvae of rotifers cultured with ω-Yeast containing different amounts of ω3 highly unsaturated fatty acids (ω3 HUFA) was compared with those cultured with respectively baker's yeast (Y-rotifer)and marine chlorella Chlorella minutissima (C-rotifer). The lower growth rate and higher mortality observed in the fish fed on Y-rotifer were clearly improved by giving them Y-rotifer cultured with ω-Yeast, supplemented with pollock liver oil at a 8% level. The dietary value of rotifers was found to be proportional to the ω3 HUFA content in the yeast and the content was effectively elevated by replacing pollock liver oil with cuttlefish liver oil or by increasing an amount of lipid from 8% to 15%, added to the culture medium of the yeast. The highest dietary value was obtained in the rotifers cultured with ω-Yeast produced by supplementing cuttlefish liver oil at a 15% level, comparable to those obtained by the larvae fed on C-rotifer. Thus, it has been demonstrated that the content of ω3 HUFA in the rotifers is the principal factor in the nutritional quality of rotifers as a living feed and that the high mortality observed frequently in red sea bream larvae in duced by feeding them Y-rotifer as a single as a single feed is due to ω3 HUFA deficiency in the fish.