The potential of liposomes as a nutrient supplement in first-feeding marine fish larvae

The ingestion rate (ng liposome larva(-1) h(-1)) of extruded [1-C-14] palmi tic acid-labelled liposomes containing physiological saline (PHS) or cod fi sh extract (CFE), was tested in 5-day-old gilthead seabream Sparus aurata a nd white grouper Epinephelus aeneus larvae. A follow-up study compared the assimilation of radioactive free fatty acid (FFA) label of these two liposo me treatments into six phospholipid and neutral lipid fractions as well as the nonlipid fraction in 5-day-old seabream. In seabream larvae, there was a 50-fold (P < 0.05) increase in the net consumption rate when fed CFE lipo somes (2305.8 ng liposome larva(-1) h(-1)) compared with liposomes containi ng physiological saline (42.7 ng liposome larva(-1) h(-1)). A similarly sig nificant(P < 0.05) but less marked pattern was also observed in the grouper larvae where the CFE treatment larvae ingested 238.5 ng liposome larva(-1) h(-1) compared with 54.3 ng liposome larva(-1) h(-1) in larvae fed the PHS liposomes. In seabream larvae ingesting CFE and PHS liposomes, radioactivi ty was found in all larval fractions analysed. However, marked treatment di fferences (P > 0.05) in assimilation were found only in the triacylglycerol fraction (3.4 and 0.6 dpm larva(-1) h(-1), respectively) and nonlipid frac tion (11.2 and 15 dpm larva(-1) h(-1), respectively).