Deficit of didocosahexaenoyl phospholipid in the eyes of larval sea bass fed an essential fatty acid deficient diet

Abstract

Larval sea bass Dicentrarchus labrax of 27 days old were reared on Artemia enriched with Super Selco©, Tuna Orbital Oil or Yeast. The first diet is commonly used in mariculture for larval rearing, the second diet was designed to deliver an optimal docosahexaenoic acid (22: 6n‐3) to eicosapentaenoic acid (20: 5n‐3) ratio, and the third diet was deficient in docosahexaenoic acid (22: 6n‐3). The eyes of these larvae were analysed after 28 days and the molecular species of the three main phospholipid classes, phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylserine (PS) determined. Eyes from larvae fed Artemia enriched with yeast showed large decreases in molecular species containing 22: 6n‐3 compared to those supplemented with tuna orbital oil, most notably in 16: 0/22: 6n‐3 PC which fell from 10.6 to 0.4%, in 22: 6n‐3/22: 6n‐3 and 18: 1/22: 6n‐3 PE which fell from 29.6 to 0.3% and from 10.8 to 1.1% respectively, and in 22: 6n‐3/22: 6n‐3 PS which fell from 34.3 to 1.7%. Molecular species containing all other fatty acids, and especially 20: 5n‐3, were elevated in eyes from the yeast‐supplemented fish. In larvae fed Artemia enriched with Super Selco, amounts of eye 22: 6n‐3/22: 6n‐3 phospholipid were slightly lower in all three phospholipid classes compared to eyes from the tuna orbital oil‐supplemented larvae. There was also a trend of decreased saturated fatty acid/22: 6n‐3 and monounsaturated fatty acid/22: 6n‐3 molecular species in all classes from the Super Selco‐supplemented fish, the deficits being made up with molecular species containing 20: 5n‐3 and 22: 5n‐3. These results are discussed in relation to larval viability with particular respect to visual function.