Impact of diets supplemented with rapeseed, soy, and sunflower oils on growth rates and the histological picture of the livers of juvenile pikeperch, Sander lucioperca (L.)

Juvenile pikeperch (120 g initial body weight) were fed a commercial diet (group CD) or experimental diets supplemented with rapeseed (group RO), soy (group SO), or sunflower (group SFO) oils for 55 days. The experimental diets were made by adding the given vegetable oil (VO) in quantities of 160 g kg^-1 feed (84% of the total raw lipid in the diet) to a base of an extruded, commercial diet (containing 30 g kg^-1 raw lipid). The dietary treatments had no significant influence on fish growth rates, apparent net protein retention (ANPR), or apparent net energy retention (ANER) (P > 0.05). The apparent lipid retention (ALR) in group SO was significantly higher than in the other groups (P < 0.05). The dietary treatments tested had a significant impact on the size of the hepatocytes and their nuclei, as well as on the nucleocytoplasmic index values (P < 0.05). No significant differences were noted in the overall image of the hepatocytes (degree of vacuolization or hepatocyte degeneration (P > 0.05)).