Substituting vegetable oil for fish oil in pikeperch diets: the impact on growth, internal organ histology, blood biochemical parameters, and proximate composition

The aim of the study was to evaluate the impact of supplementing feed with vegetable oil on the growth, blood biochemical parameters, and histological structures in the liver, intestines, spleen, and the chemical composition of juvenile pikeperch. The fish were fed isoprotein and isoenergetic feeds with 190 g kg(-1) of fat. Feeds was supplemented with fish oil (FO), linseed oil (LO), or peanut oil (PO) in the same quantities (160 g kg(-1)). The fourth group of fish was fed commercial feed (CF). Feeding juvenile pikeperch with various lipid quantities did not result in differences in fish growth. The highest apparent protein retention and the lowest apparent lipid retention values were observed in pikeperch fed feed with LO. LO resulted in a low content of palmitic acid and high of alpha-linolenic acid in the feed and was linked to a significantly lower lipid and higher protein content in the viscera, and pathological changes in the liver. Vegetable oils increased the viscero-somatic index value and activity in aspartate aminotransferase and alanine aminotransferase, ceruloplasmin, and higher bilirubin content. Supplementation with vegetable oils in pikeperch feed lowered the content of eicosapentaenoic and docosahexaenoic acids in fillets compared to feed with FO.