EFFECTS OF DIETARY OXIDIZED OIL FOR PENAEUS-JAPONICUS

Larval and juvenile prawns P. japonicus were fed test diets containing fresh or oxidized corn, squid liver, and pollack liver oils. In the l arval study, the peroxide values (POV) of test oils added to each of t he test diets were respectively 0.6, 24.6, 69.8 meq/kg oil for fresh ( Of), slightly oxidized (Os), and mildly oxidized (Om) oils for the com oil-based diets, 0.3, 19.8, 37.6 meq/kg oil for corresponding squid l iver oil-based diets, and 1.7, 25.5, 38.6 meq/kg oil for corresponding pollack liver oil-based diets. In the juvenile study, these figures a re respectively 0.6, 29.9, 44.3 meq/kg oil for com oil-based diets, an d 1.9, 35.3, 45.8 meq/kg oil for pollack liver oil-based diets. Os and Om oils delayed development, reduced postlarval size, and weakened th e postlarva, although mortality was not so high. A POV of more than 13 meq/kg seems to be a critical level for larvae whereas a POV of 35 me q/kg was still within the allowable degree of oxidation for juveniles. The size of postlarva1 was reduced further when fed diets containing marine Os or Om oils compared to vegetable oil such as com oil.