TENTATIVE UTILIZATION OF SPIRULIN ALGAE AS A SOURCE OF CAROTENOID PIGMENTS FOR RAINBOW-TROUT

Spirulin algae contain β-carotene (26%), β-carotene-5,6-epoxide (5%), echinenone (7%), cryptoxanthin (23%), zeaxanthin (9%) and myxoxanthophyll (24%). The total content of the pigments amounts to 1.7 mg/g of dry algae. The incorporation of spirulin algae in rainbow trout diet (0, 2.5, 5, 10 and 20% w/w) causes a yellow-brown pigmentation of the fish in 56 days. While no carotenoid pigment can be identified in trout muscle, echinenone, cryptoxanthin and zeaxanthin are found in the skin. The rainbow trout is thus unable to fix all natural carotenoids, in particular glycosyl xanthophylls. From a quantitative point of view, although the increase in carotenoid percentage in trout skin is important (11 times the initial value), it is relatively small compared to the large content of spirulin algae in the diets. A supplementary feeding of spirulin algae to trout, for pigmentation purposes only, is not applicable in intensive fish culture: nevertheless one must not discount a possible synergic effect. © 1979.