Effect of dietary DHA/EPA ratio on the early development, antioxidant response and lipid metabolism in larvae of Siberia sturgeon (Acipenser baerii, Brandt)

A 30-day growth study was conducted to evaluate the impacts of the dietary DHA/EPA ratios on growth performance, antioxidant and lipid metabolism of Siberian sturgeon larvae. Four isonitrogenous and isoenergetic microcapsuled diets were formulated with various DHA/EPA ratios as 0.73 (R-0.73), 1.25 (R-1.25), 1.75 (R-1.75) and 2.33 (R-2.33). The results showed that the final body length, final body weight, specific growth rate and survival in the group R-2.33 were highest (p < 0.05), while there were no significant differences on viscerosomatic index and condition factor among all groups. Visceral catalase activity of groups R-2.33 and R-1.75 was significantly higher than that of groups R-0.73 and R-1.25, but superoxide dismutase, total antioxidant capacity, malondialdehyde, total cholesterol, triglycerides and high-density cholesterol were not different among groups. The gene expression of PPAR alpha and lipoprotein lipase had no difference among groups, but the expression of hepatic lipase gene in groups R-1.75 and R-2.33 was significantly lower than that in group R-0.73 as a negative feedback of high dietary DHA intake. In conclusion, growth performance was improved but kept stable antioxidant response in visceral mass with increased levels of DHA/EPA ratios from 0.73 to 2.33 for Siberian sturgeon larvae. Improving DHA/EPA ratios is a benefit for larvae to selectively deposit more DHA, then EPA and ARA than MUFA in the body to meet the requirement for early development.