Enhanced absorption of docosahexaenoic acid (DHA, 22:6n-3) in Artemia nauplii using a dietary combination of DHA-rich phospholipids and DHA-sodium salts

Abstract

The effects of surface-active agents such as phospholipids (PL) and salts of long chain fatty acids in enrichment lipids on emulsification, and hence digestion and absorption of essential fatty acids (EFA) were studied. The advantages obtained by using a mixture of docosahexaenoic acid (DHA, 22:6n-3)-rich phospholipids (DHA-PL) and DHA-salts in the process of live feed enrichment are reported on. Enrichment diets at equal levels of DHA, but with varying proportions of DHA-rich triacylglycerols (DHA-TAG), DHA-PL and DHA-sodium salt (DHA-Na) isolated from heterotrophicaly grown Crypthecodinium sp . algae were fed to instar-II stage Artemia nauplii. Artemia nauplii survival and lipid content after 16 h of enrichment were 74.0±7.8% and 24.3±0.6% (dry weight) respectively, and not significantly affected ( P>0.05) with increasing dietary quantities of PL and DHA-salts (up to 40 and 30%, respectively). Artemia lipid class composition was independent of dietary phospholipid level. However, higher proportions of polar lipid fraction was evident in Artemia lipids with the addition of DHA-Na. Dietary inclusion of 20% PL or a mixture of 10% PL and 10% DHA-Na resulted in maximal ( P<0.05) absorption of dietary DHA by the Artemia (27.5±2.6 mg/g dry weight) with a DHA to eicosapentaenoic acid (EPA, 20:5n-3) ratio greater than 3. Furthermore, PL was the most efficient dietary fraction to deliver DHA to Artemia nauplii as compared to TAG or unesterified delivery forms.