Astaxanthin compared with B-Carotene in black tiger shrimp farming

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Maintaining the natural color of shrimp is an important commercial issue, directly related to consumer acceptance or rejection and the market price of the product. In crustaceans, color is produced by carotenoid pigments, with the main pigment being free or esterified astaxanthin. Astaxanthin can shift from reddish-orange to brownish, greenish, or pale bluish hues through the formation of carotenoprotein complexes. The red color is revealed when shrimp are cooked.Common plant sources can synthesize lycopene and β-carotene but not astaxanthin. Black tiger shrimp cannot synthesize carotenoids de novo but can metabolize dietary β-carotene and canthaxanthin into astaxanthin that accumulates in the body. The desired color is achieved by supplementing astaxanthin in the feed, as it is the carotenoid responsible for the natural color.The cost of synthetic astaxanthin is very high, significantly increasing feed and production costs. Therefore, improving the efficiency of astaxanthin or finding a cheaper alternative method to achieve the desired color is commercially necessary. Some studies have shown that black tiger shrimp can metabolize dietary β-carotene into astaxanthin. This suggests that if the conversion is efficient enough, feeding β-carotene or β-carotene-rich products could be a cheaper alternative to achieve the desired color in crustaceans.However, no study has compared the effects of supplemental astaxanthin and β-carotene on the coloring ability of black tiger shrimp. Moreover, the efficiency of carotenoid utilization for flesh coloration is very low, only about 5-15% of the dietary carotenoid is used for coloration.Besides their coloring effect, carotenoids play other important physiological roles as antioxidants and in enhancing the resistance of shrimp to stressors such as hypoxia, salinity, ammonia, and live transportation.

Materials and Methods

Experiment 1: Juvenile black tiger shrimp with an initial weight of around 2.07 g were fed 5 different diets: a control diet without carotenoids; a diet supplemented with 0.1% astaxanthin; a diet with 0.1% astaxanthin and 1% cholesterol; a diet with 0.25% β-carotene; and a diet with 0.25% β-carotene and 1% cholesterol.Experiment 2: After 60 days of feeding, shrimp were exposed to air for 36 hours to simulate live transportation. Immune parameters, oxidative stress, and gene expression were then evaluated.Parameters monitored: growth, survival, whole-body and muscle proximate composition, carotenoid content, color score, apparent digestibility coefficients, tissue carotenoid retention efficiency, total hemocyte count, clotting time, malondialdehyde and carbonyl protein in hepatopancreas, Hsp70 and HIF-1α gene expression.


Experiment 1:

  • Growth and survival were highest in shrimp fed the astaxanthin and cholesterol-supplemented diets.
  • No differences in apparent digestibility coefficients of dry matter, protein, energy, and carotenoids among diets. Carotenoid digestibility was high (>90%) in carotenoid-supplemented diets. Cholesterol supplementation did not improve carotenoid digestibility but increased tissue carotenoid retention in the astaxanthin diet but not the β-carotene diet.
  • Total hemocyte count was lower in shrimp fed the control diet compared to carotenoid-supplemented diets. Conversely, clotting time was higher in the control diet.
  • Malondialdehyde levels in the hepatopancreas were higher in shrimp fed the control diet compared to carotenoid-supplemented diets.
  • No differences in Hsp70 and HIF-1α gene expression in the hepatopancreas among diets.

Experiment 2:

  • No mortality in any diet after 36 hours of simulated live transportation.
  • Total hemocyte count decreased significantly in shrimp fed the control and β-carotene diets after experiment 2, but remained unchanged in the astaxanthin diets.
  • Clotting time increased significantly in the control diet after experiment 2 and remained unchanged in carotenoid-supplemented diets.
  • Malondialdehyde and carbonyl protein levels in the hepatopancreas were higher in experiment 2 compared to experiment 1.
  • Hsp70 and HIF-1α gene expression in the hepatopancreas was significantly lower in shrimp fed the control diet compared to other diets.


The growth of black tiger shrimp was affected by the experimental diets. Astaxanthin was more effective than β-carotene in improving growth and survival of shrimp.Whole-body and muscle protein content increased slightly when astaxanthin or β-carotene was supplemented. Whole-body and muscle lipid content was higher in shrimp fed the β-carotene diets compared to astaxanthin or control diets.The high digestibility and low tissue retention of carotenoids means that dietary astaxanthin can be efficiently digested in the digestive tract of black tiger shrimp, but not deposited in tissues as a pigment. Cholesterol supplementation may increase the bioavailability of astaxanthin in shrimp but not β-carotene.Dietary carotenoid supplementation was associated with enhancing the ability of shrimp to cope with hypoxia, salinity, ammonia, and air exposure during live transportation stresses. Astaxanthin was better than β-carotene in maintaining total hemocyte count and clotting time after air exposure.Hsp70 and HIF-1α gene expression in shrimp fed the control diet was significantly lower than in carotenoid-supplemented diets under hypoxic conditions, indicating that dietary astaxanthin or β-carotene could partially alleviate the hypoxic stress response.


Data on growth assessment and immune response showed that astaxanthin was better than β-carotene in improving growth, health status, and ability to cope with air exposure stress in black tiger shrimp. Replacing astaxanthin with β-carotene could provide a new, safe, and effective aquaculture technique for future aquaculture production. Moreover, cholesterol supplementation could enhance the efficacy of astaxanthin but not β-carotene.



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