Effect of feeding astaxanthin with different E/Z‐isomer ratios on astaxanthin accumulation in Pacific white shrimp Litopenaeus vannamei

Astaxanthin is traditionally utilized in crustacean aquaculture to enhance the characteristic pink‐red color of these species. It has been reported that the bioavailability and body accumulation efficiency of astaxanthin differ based on its E/Z‐isomer species, and these trends vary widely among animal species. This study investigated the influences of feeding astaxanthin having different E/Z‐isomer proportions on astaxanthin accumulation in Pacific white shrimp Litopenaeus vannamei. Z‐Isomer‐rich astaxanthin was prepared from the synthetic (all‐E)‐astaxanthin standard by thermal treatment, and the prepared all‐E‐isomer‐rich astaxanthin pellets (E‐AST‐P; total Z‐isomer proportion = 4.7%) and Z‐isomer‐rich astaxanthin pellets (Z‐AST‐P; total Z‐isomer proportion of astaxanthin = 81.8%) were fed to L. vannamei for 8 weeks. The feeding of Z‐AST‐P significantly improved the body astaxanthin concentration compared to those fed the control pellets without adding astaxanthin isomers and E‐AST‐P; the astaxanthin concentrations after the 8‐week treatments of the control pellets, E‐AST‐P, and Z‐AST‐P were 7.3 ± 0.5, 6.2 ± 1.8, and 12.3 ± 1.3 µg g–1, respectively. This result suggested that astaxanthin Z‐isomers have higher bioavailability and/or body accumulation efficiency than (all‐E)‐astaxanthin in L. vannamei. Practical Applications: The bioavailability of astaxanthin is generally very low, which is a critical issue for its use in crustacean aquaculture. In this study, we found that feeding a pellet rich in astaxanthin Z‐isomers showed a greater accumulation efficiency of astaxanthin in the whole body of L. vannamei than that fed a pellet rich in the all‐E‐isomer. Thus, the use of Z‐isomer‐rich astaxanthin feeds would contribute to improving the quality of crustacean and reducing the feed costs (i.e., reduction of the use amount of astaxanthin). The effect of feeding astaxanthin with different E/Z‐isomer ratios on astaxanthin accumulation in Pacific white shrimp Litopenaeus vannamei was investigated. The feeding of Z‐isomer‐rich astaxanthin pellets significantly improved the body astaxanthin concentration compared to that fed the all‐E‐isomer‐rich astaxanthin pellets.