Use of the beta-carotene rich alga Dunaliella bardawil as a source of retinol.

Dunaliella bardawil, a beta-carotene accumulating halotolerant alga, has been tested as a source of retinol in a chick diet. Chicks were fed diets deficient in retinol or supplemented with retinol, synthetic beta-carotene or dry algae. After an initial lag, chicks grew equally well on diets supplemented with algae, retinol or beta-carotene. Serum and liver analyses revealed a normal content of retinol in all chicks except those grown on the retinol-deficient diet. Chicks fed the algae-supplemented diet contained lutein but no beta-carotene in their serum, even though the ratio of beta-carotene to lutein in the algae was over 15:1. Laying hens fed with an algae-supplemented diet showed enhanced egg yolk colour attributable to a higher lutein content. No beta-carotene was present in the egg-yolk. These studies demonstrate the possibility of using dried Dunaliella bardawil as a dietary supplement which can fully satisfy the retinol requirement and also serve as a yolk-colour enhancing agent.