Effects of dietary supplementation with Haematococcus pluvialis cell powder on coloration, ovarian development and antioxidation capacity of adult female Chinese mitten crab, Eriocheir sinensis

The red color of Chinese mitten crab, Eriocheir sinensis, which is largely dependent on the presence of carotenoid pigments (predominantly astaxanthin), is an important attribute affecting its consumer acceptability and market value. The green algae Haematococcus pluvialis, rich in natural astaxanthin, is considered to be an important feed additive for crustacean coloration. This study was conducted to investigate the effects of dietary supplementation of H. pluvialis powder on coloration, ovarian development and antioxidation capacity of adult female E. sinensis. Four experimental diets were formulated to contain 0, 0.2%, 0.4% and 0.6% of H. pluvialis cell powder. Therefore, there were four treatments (defined as T1-T4), and each treatment had three replicate tanks (12 females tank− 1). The results showed that dietary H. pluvialis powder had no significant effects on survival, gonadosomatic index (GSI) and hepatosomatic index (HSI) (P > 0.05). The redness (a*) of ovaries and carapace as well as the contents of total carotenoid and astaxanthin in ovaries, hepatopancreas and carapace increased significantly with increasing dietary H. pluvialis powder, while a decreasing trend was found for the lightness (L*) and yellowness (b*) of ovaries (P < 0.05); the highest and the lowest a* and b* of hepatopancreas were found for T3 and T1, respectively (P < 0.05). For antioxidant and immune parameters, T3 had the highest levels of catalase (CAT), glutathione peroxidase (GPX), peroxidase (POD), hemocyanin (Hc) and γ-glutamyl transpeptidase (γ-GT) in the serum, while there was a significant decrease for the content of malondialdehyde (MDA) in serum, as well as in the levels of nitric oxide (NO), MDA and acid phosphatase (ACP) in hepatopancreas (P < 0.05). Dietary H. pluvialis powder had significant effects on the contents of moisture and crude protein in ovaries and muscle as well as hepatopancreatic ash level. In conclusion, dietary H. pluvialis powder had no significant effect on ovarian development, but enhanced coloration, antioxidation capacity and improved protein content in ovaries and muscle of female E. sinensis. These results suggested the appropriate level of dietary natural astaxanthin in feed was approximately 60 mg kg− 1.