Effects of dietary oxidized fish oil on growth performance and antioxidant defense mechanism of juvenile Rhynchocypris lagowski Dybowski

Five isonitrogenous and isolipidic diets containing fresh fish oil and four degrees of oxidized fish oil (POV:100; 200; 300; 400) were formulated to investigate the effects of dietary oxidized fish oil on growth performance, the antioxidation function of Rhynchocypris lagowski Dybowski. After an 8-week feeding trial, fish fed oxidized oil diets obtained significantly lower weight gain and specific growth rate due to their lower feed efficiency and protein efficiency. With the increasing of fish oil oxidation level, MDA level of the liver significantly increased, the antioxidant enzymes (T-SOD, CAT, GSH-PX) activities and GSH content of the liver were significantly decreased, and CAT, CuZn-SOD and GSH-PX mRNA levels of the liver showed the same change trend. Further analysis showed that, Keap1 mRNA level of the liver was increased, and the Nrf2, Maf, HO-1 mRNA levels of the liver were significantly decreased. However, some parameters showed a reverse trend after the 4-week feeding. In conclusion, by checking indicators of growth performance, the main antioxidant parameters, the related genes mRNA levels, the present study showed that dietary oxidized fish oil can induce oxidative damage in R. lagowski Dybowski.