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Astaxanthin: An important microingredient in aquaculture feeds Terry W. Snell, Matthew Carberry, John Carberry, Tim Wilson, Sustainable Aquatics
Based on 20 years’ experience breeding hundreds of marine species in our Sustainable Aquatics hatchery, we conclude that adding di-esterified 3S, 3’S astaxanthin as a feed micro-ingredient makes fish more resistant to disease, eliminates the need for antibiotics in the hatchery, improves fish survival, increases growth rates, boosts reproduction and provides exceptional color. We have learned how to produce di-esterified 3S, 3’S astaxanthin from Haematococcus pluvialis oil that is highly bioavailable and low cost. Astaxanthin from the green alga H. pluvialis is synthesized at an end of the green phase to prepare for encystment of cells so that they can survive desiccation (Kobayashi et al. 1997). This encystment converts the algal cell into a 60 µm cyst which is indigestible and resistant to UV. The widely used supercritical CO2 astaxanthin extraction process breaks cysts down to 5 µm, but denatures astaxanthin in the process. Astaxanthin is most bioactive and stable if it is esterified and not exposed to high temperatures. We have patented a low-temperature extraction process to break H. pluvialis biomass into particles less than 100 nanometers. The hydrophobic astaxanthin
naturally associates with fatty acids, becomes esterified, and self-assembles first into micelles and then liposomes. This lipid-rich, nano-emulsion allows astaxanthin to transit the digestive tract and bloodstream, increasing its bioavailability from 48-700 times.
Astaxanthin requirements in salmon A recent demonstration of the value of astaxanthin as a feed additive in aquaculture is illustrated in our work with Atlantic salmon. Sustainable Aquatics has been developing husbandry, water engineering and nutrition protocols for salmon RAS aquaculture. When attempting to improve salmon feeds, it is important to understand the natural diet of all phases of the salmon life cycle. Salmon juveniles start exogenous feeding after about 420 degree-days in the gravel of river bottoms (redd) where they were originally spawned (Solberg et al. 2014). In contrast, the industry typically starts exogenous feeding at 840-degree days at 6°C. This feeding regime starves the alevins for about 110 days
Figure 1. Atlantic salmon growth from 5 through 25 weeks post-hatch.
Aquafeed: Advances in Processing & Formulation Vol 14 Issue 2 2022
