DIETARY SODIUM SELENITE, SELENIUM YEAST AND SELENIUM-ENRICHED SPIRULINA ON GROWTH, ANTIOXIDANT CAPACITY AND TISSUE SELENIUM CONTENTS OF JUVENILE HYBRID STURGEON (ACIPENSER BAERII ♂×ACIPENSER SCHRENCKII ♀)

This experiment aimed to investigate the effects of different sources and levels of dietary selenium additives on the growth, antioxidant capacity and tissue selenium contents of hybrid sturgeon juveniles. Three sources of selenium were selected as sodium selenite, selenium yeast and selenium-enriched spirulina at two different levels of 0, 0.4 and 1.2 mg/kg, to prepare control diet (C) and sodium selenite supplemented diets (S1, S2), selenium yeast supplemented diets (Y1, Y2) and selenium-enriched spirulina supplemented diets (P1, P2). Hybrid sturgeon juveniles (initial body weight at about 7.8 g) were raised for 62d using the experimental diets. The results showed that different selenium sources and levels had no significant effects on the specific growth rate and feed efficiency of juvenile hybrid sturgeon (P>0.05), however the selenium contents in the whole fish, liver, muscle and vertebra of the hybrid sturgeon in the high yeast selenium and high selenium-enriched spirulina supplemented groups were significantly higher than those in the control group (P<0.05). Sodium selenite supplementation significantly increased the selenium contents in the whole fish and liver (P<0.05), but had no significant effects on the selenium contents in muscle and vertebra (P>0.05). Muscle selenium content in sodium selenite group was significantly positively correlated with whole fish selenium content (P<0.05), and significantly negatively correlated with liver selenium content (P<0.05). Meanwhile, the plasma GSH-Px activity of the juvenile hybrid sturgeon in the high selenium supplemented groups was significantly higher than that in the control and low selenium supplemented groups (P<0.05), furthermore, the MDA contents in the selenium-enriched spirulina supplemented group were significantly lower than those in the sodium selenite supplemented groups (P<0.05). Plasma GSH-Px activity was positively correlated with muscle (P<0.01), vertebra (P<0.01) and hepatic selenium content (P<0.05). The plasma total protein (TG) and total cholesterol (TC) contents in the selenium yeast supplemented groups were significantly higher than those in the control group (P<0.05). In conclusion, high-level selenium supplementation can increase the selenium contents of whole fish and liver, but the accumulation patterns of different types of selenium in fish are inconsistent. High-level organic selenium (selenium yeast and selenium-enriched spirulina) supplementation is more likely to accumulate in muscle and vertebrae than inorganic selenium (sodium selenite). Moreover, high-level selenium supplementation could significantly improve the antioxidant capacity of hybrid sturgeon, and different selenium sources had no significant effects on antioxidant properties.