Fatty acid composition and dietary value of rotifer Brachionus plicatilis fed on waste lipid treated with Aspergillus terreus.

Abstract

Attempts were made to improve the dietary value of rotifer fed on baker's yeast by direct feeding of microbial-treated lipid. The nontreated lipid (NTL) from mackerel waste juice was treated with Aspergillus terreus, and the treated lipid (TL), NTL and pollack liver oil (PLO) were emulsified with sea water and proteinous sediment from the waste juice. The emulsified lipids and yeast were fed to rotifers and the proximate and fatty acid compositions of the rotifers were determined. Furthermore, ayu larvae were reared with the rotifers fed on baker's yeast (BY) with or without TL or NTL, and their growth and survival rate were compared. The rotifers fed on the lipids showed similarly higher lipid content than the initial rotifer. However, the ω3 HUFA content of rotifer fed on TL (BY+TL rotifer) was higher than that of the rotifer fed on NTL (BY+NTL rotifer) and similar to rotifer fed on PLO (BY+PLO rotifer). The total body length of larvae reared with BY+NTL rotifer (BY+NTL group) was significantly inferior to that of BY+TL group at the end of the 25 days feeding trial.The survival rates of BY+NTL group in feeding trial and handling tests were also lower than those of BY+TL group. The larvae reared with rotifer fed on BY only were the lowest of all the groups in the growth and survival rate.