Dietary lipid levels affect growth performance, lipid metabolism, antioxidant and immune status of Amur sturgeon, Acipenser schrenckii

The proper lipid content in the diets is crucial for fish growth and health. However, the appropriate lipid requirement of Amur sturgeon has not been systematically studied. This study was aimed to explore the effects of dietary lipid levels on growth performance, lipid metabolism, antioxidant and immune status of juvenile Amur sturgeon (Acipenser schrenckii). Six isonitrogenous diets containing 5.11% (L5), 8.87% (L9), 12.96% (L13), 16.93% (L17), 20.84% (L21) and 24.88% (L25) lipid were fed to Amur sturgeon (4.16 +/- 0.07 g) for 10 weeks. The fish in L21 group had the highest growth, feed utilization and survival rate. Based on the broken-line regression analysis of WGR, the lipid requirement for juvenile Amur sturgeon was 20.31%. HSI, hepatic crude lipid content and serum TG, TC and LDL-C contents elevated significantly with the increase of dietary lipid. Higher hepatic SOD, Anti -O2.-were found in L21 group, while MDA in both serum and liver maintained an upward trend with dietary lipid increase. The expression levels of fasn and lpl were suppressed when dietary lipid levels reached or exceeded 16.93%. While cpt1 alpha and ppar alpha were up-regulated, and peaked in L21 group, but down regulated in L25 group. The expression level of il1 beta was on the rise as dietary lipid increased, but il10 and tgf beta 1 showed a downward trend in high lipid groups. In conclusion, based on WGR, a lipid level of 20.31% in the diet was optimal for juvenile Amur sturgeon. Low (5.11%-12.96%) or high lipid (24.88%) diet decreased growth, feed utilization and survival rate. High lipid (24.88%) diet induced excessive lipid deposition, leading to intense oxidative stress, lipid metabolism disorder and inflammation.