EFFECTS OF HIGH OXIDIZED FISH OIL ON GROWTH AND LIPID METABOLISM OF RICE FIELD EEL Monopterus albus

Oil is important for lipid metabolism and fish growth. The unsaturated fatty acids in oil are readily susceptible to autoxidation and rancidity, following by the oxidative and rancid products like peroxides and malondialdehyde. These products are toxic to fish, and shows greatly negative impacts on nutrient metabolism and further lead to excessive lipid deposition. The present study was conducted to the effects of high oxidized fish oil levels and supplementation of apple polyphenol (AP) and taurine (TA) on the growth performance, antioxidant and lipolysis of rice field eel.

Fish oil was heated up to 70 °C with constant aeration and POV was monitored every 4 h until it reached 600 and 800 meq/kg values. Control group fed with basic diet, and POV600 and POV800 groups respectively fed with diet containing 600 and 800 meq/kg oxidized fish oil, respectively. Based on the diet of POV600 group and POV800 group, the diet of AP and TA groups was supplemented with 0.5% apple polyphenol or 0.2% taurine, respectively. Each group has 3 replicates capes with a density of 100 eels in per cage, which was placed in a natural water environment.

The results showed that: the liver cells of eels fed high level oxidized oil are obviously degenerated together with numerous lipid vacuoles (Fig.1), meanwhile the intestinal structure was incomplete and the number of goblet cells decreased sharply following by a large number of vacuoles (Fig.2); the oxidized oil could affect lipolysis by AMPK in liver through AMPK-ACC-CPTⅠ and AMPK-lipin-PPARα-CPTⅠ pathways. The results of this study established an important theoretical foundation for the study of AMPK-mediated lipid catabolism.