Phospholipids in Marine Larval Rearing

Recent studies have shown that fish larvae require not only a certain quantitative amount of dietary phospholipid (PL) in their feed, but they also depend on the quality of the dietary PL, and their docosahexaenoic acid (DHA) content is particularly important for normal growth and functional development. The most commonly used live feeds in aquaculture, rotifers (Brachionus sp.) and brine shrimp (Artemia sp.), do not contain adequate amounts of DHA in their PL. Therefore, there is an emerging need to learn more on how PL of live feed organisms can be efficiently enriched. In this chapter, we discussed the factors that could affect the enrichment of DHA in PL of live feed and suggested some strategies that could increase the DHA levels in PL of rotifers. The mechanism behind the PL requirement of fish larvae is not well understood and the overall objective of our studies has been to obtain more knowledge of ontogenesis of PL synthesis capability of early stages of Atlantic cod Gadus morhua. Transcriptome analysis of larvae in different stages was carried out using microarray, to evaluate the effect of development on the expression of key genes of PL biosynthesis. Moreover, labeled lipid precursors were tube fed to cod larvae to evaluate their capacity of PL synthesis. The larvae showed relatively high biosynthesis ability of PL compared to neutral lipids. Our overall data suggested that besides the possible limited de novo PL synthesis ability in the intestine, other metabolic constraints should also be considered.