Effect of dietary Rhodiola rosea extract on antioxidant system and anti-low salinity stress of Litopenaeus vannamei

In order to investigate the effect of Rhodiola rosea extract on the antioxidant system and anti-low salinity stress of Litopenaeus vannamei, four levels of R.rosea extract were designed (0 mg·kg^–1, 300 mg·kg^–1, 1 000 mg·kg^–1 and 3 000 mg·kg^–1). We have fed the shrimps for 28 d and carried out a 72-hour low salinity (10) stress test to analyze the antioxidant capacity including total antioxidant status (T-AOC), glutathione peroxidase (GSH-Px), catalase (CAT) as well as gene expression of GSH-Px and CAT in hepatopancreas of shrimps. The results show that enzyme activities of GSH-Px and CAT and gene expression of GSH-Px were significantly induced in hepatopancreas of shrimps fed with R.rosea extract at different time intervals (P<0.05). The antioxidant indices of shrimps of the control group at low salinity stress at 24^th hour varied greater than those of shrimps of supplemental R.rosea groups. For the shrimps fed with dietary R.rosea extract at low salinity stress at 72^nd hour, the activities of T-AOC, CAT as well as gene expression of GSH-Px and CAT of hepatopancreas were significantly higher than those in the control group (P<0.05). The GLM analysis results show significant interaction between the effects of R.rosea extract level and time on the antioxidant indices. In conclusion, R.rosea extract can alleviate drastic variation of antioxidant indices in the hepatopancreas of shrimps at the early stress stage effectively. Besides, the antioxidant capacity of shrimps fed with supplemental R.rosea extract was significantly improved at the late stress stage. Thus, the R.rosea extract has the potential to become an anti-stress feed additive.