UTILIZATION OF MICROALGAL ASTAXANTHIN BY RAINBOW-TROUT (ONCORHYNCHUS-MYKISS)

The effect of supplementing trout diets with astaxanthin-rich microalgae was studied in a 100-day feeding trial. Intact (Whole) and homogenized (Broken) preparations of spores from the green alga Haematococcus pluvialis were observed to result in significant deposition of total carotenoid and astaxanthin, as well as visual enhancement of the flesh colouration in trout. No significant differences were seen in trout growth. The highest levels of total carotenoid, astaxanthin and colouration in trout flesh were found in groups fed synthetic astaxanthin (Roche Carophyll Pink), followed by the Broken and Whole rations. These differences were likely to have been a result of a high level of esterified astaxanthin in the alga and poor digestibility of intact spores. Total carotenoid levels were also measured in the trout skin, with significantly higher levels noted in the Carophyll Pink and Broken treatments.