Effects of natural astaxanthin from microalgae and chemically synthetic astaxanthin supplementation on two different varieties of the ridgetail white prawn (Exopalaemon carinicauda)

This study evaluated the effects of natural astaxanthin (Ax) from microalgae (Haematococcus pluvialis) and synthetic Ax supplementation on growth performances, pigmentation, Ax content and antioxidant capacity in two varieties of the ridgetail white prawn (Exopalaemon carinicauda). Experimental animals were fed with nine experimental diets for 56 days. It showed that dietary Ax did not influence the growth performances of the wild-typed prawn (p > 0.05), while 400 mg kg⁻¹ Ax supplementation significantly improved the survival rate and total weight gain of the new variety (p < 0.05). Meanwhile, the new variety showed improved growth performances in comparison with the wild-typed prawn when fed with 200 or 400 mg kg⁻¹ Ax. Ax supplementation significantly enhanced the body pigmentation, including redness and yellowness of the new variety and the wild-typed prawn, but the improvement efficiency of natural Ax was higher than that of synthetic Ax. Ax supplementation also significantly increased the contents of free Ax and total Ax in abdominal muscles of the two varieties, and a maximum increase of free and total Ax content by 16.2 and 17.8 folds in the new variety was gained when they were fed with 400 mg kg⁻¹ natural Ax. The redness was positively correlated with the content of free Ax and total Ax. Moreover, Ax supplementation significantly improved the antioxidant capacity by increasing the activity of total antioxidant capacity, decreasing the activity of catalase, total superoxide dismutase, glutathione peroxidase, and malonadehyde content in both the new variety and the wild-typed prawn (p < 0.05). Based on the data obtained from the present study, the optimal level of natural Ax supplementation in the new variety was 100 mg kg⁻¹ or above, and around 200 mg kg⁻¹ for synthetic Ax. Natural Ax should be an alternative choice in improving performances of the new variety of E. carinicauda.