The Effect And Mechanism Of Dietary Supplementation Of Astaxanthin To White Shrimp, Litopenaeus Vannamei

In this paper, astaxanthin was extracted from the green alga Haematococcus pluvialis which were determined quantitatively by HPLC and then astaxanthin was supplemented in basal diets of Litopenaeus vannamei. In order to study the effect of astaxanthin on physiological and biochemical characters of L. vannamei and to explore its mechanism, this paper focus on the three points as followed:(1) The effects of dietary supplementation of astaxanthin on growth, survival and antioxidant capacity; (2) The effects of astaxanthin on the resistance to ammonia stress; (3) Photoprotective effect of astaxanthin on L. vannameiThe astaxanthin was added to the diets of L. vannamei with different supplementation level (0,20,40,60,80 and 100 mg/kg diet) for 7 weeks, which aims to determine the effects of astaxanthin on growth, survival and antioxidant capability. The results showed that astaxanthin could increase the survival rate and the specific growth rate (SGR), and the supplementation level of 80 mg/kg group was higher than other groups. The specific growth rate of 80 mg/kg group was improved significantly (P<0.05), while the survival rate between experimental and control groups had no significant differences (P>0.05). Total antioxidant capability (T-AOC) of experimental group shrimps were significantly increased (P<0.05), however the trend was ceased after 4 weeks. Superoxide dismutase (SOD) activity and catalase (CAT) activity of experimental group shrimps were significantly lower (P<0.05) than that of control groups, which decreased with increasing feeding days, however the trend was changed to gradually increasing 4 or 5 weeks later. Based on survival rate, specific growth rate and antioxidant capability, supplementation of 80 mg/kg astaxanthin would be most effective and the optimal feeding time was 4 weeks.The astaxanthin was added to the diets of L. vannamei with different supplementation level (0,80 mg/kg diet) for 21 days under ammonia stress (1mg/L). The results showed that astaxanthin could significantly increase the survival rate and SGR of experimental group (P<0.05). Total hemocyte counts (THC) and phagocytic activity (including phagocytic percentage and phagocytic index) of control group shrimps were decreased and hemolymph clotting time were increased significantly under ammonia stress; THC of experimental group shrimps were decreased at the beginning and then returned to normal levels after 7 days, phagocytic activity and hemolymph clotting time remained stable at the same time. T-AOC of control group shrimps were decreased but SOD and CAT activities were increased under ammonia stress. In contrast, T-AOC of experimental group shrimps were slightly decreased at the beginning and then increased, and two kinds of enzyme activity decreased slightly. The results proved that the resistance of L. vannamei against ammonia stress had been improved by dietary astaxanthin. Astaxanthin could improve the survival rate of shrimps and maintain the stability of hematological and antioxidant systems.The astaxanthin was added to the diets of L. vannamei with different supplementation level (0,80 mg/kg diet) for 4 weeks, which aims to investigate the radiation damage of cells of muscle by ultraviolet A (UVA) and the protective effects of astaxanthin. A primary cell culture system was developed for the muscle cells of L. vannamei (M199,650 mmol/L, pH 7.2). UVA exposure caused an important decrease in survival rate and T-AOC and an important increase in SOD activity and CAT activity. Astaxanthin increased survival rate and T-AOC and decreased the activity of antioxidases. The experiments showed that the muscle cells of L. vannamei were damaged by UVA radiation and astaxanthin has potential photoprotective effects form UVA induced damage on cultured cells.In brief, as a non-nutritive immunostimulants, astaxanthin (80 mg/kg) could significantly increase the survival rates and SGR, improved antioxidant capability and the resistance of L. vannamei against ammonia stress. Astaxanthin also can serve as a photoprotectants, which could help to protect the cells from being damaged by UVA.