Effect of vitamin B9 (folic acid) levels on growth and some serum biochemical indices and liver enzymes of Siberian sturgeon (Acipenser baerii)

To investigate the effect of dietary folic acid (FA) on growth performance, serum biochemical indices and liver enzymes status of Siberian sturgeon (Acipenser baerii Brandt 1896), six isonitrogenou and isolipidic experimental diets were formulated to contain graded levels of FA including 0.60, 1.63, 2.71, 3.59, 4.82 and 5.68 mg/kg). Each diet was fed to fish (4.36±0.18g) in a flow through water system for 8 weeks. Examined indices in this study included relative growth rate, daily growth coefficient, feed conversion ratio as well as amount of cholesterol, triglyceride, alkaline phosphatase activity, glutathione S-transferase and malondialdehyde. The results showed that the use of folic acid at the level of 2.71mg/kg increased the growth performance and daily growth coefficient of Siberian sturgeon and caused a statistically significant increase in daily growth percentage of fishes (P<0.05). On the other hand, feed conversion ratio decreased with increasing dietary folic acid level from 0.60 to 2.71 mg/kg and then increased. No statistically significant difference was observed in the alkaline phosphatase activity of fish fed with different levels of folic acid (P>0.05). Glutathione S-transferase activity was not affected by different concentrations of dietary folic acid. Furthermore, different concentrations of dietary folic acid could not make a statistically significant effect on the level of triglyceride, cholesterol and malondialdehyde (P>0.05). The folic acid requirement of Siberian sturgeon based on the daily growth coefficient was estimated to be 1.65 mg/kg diet.