Lipid classes from marine species and meals intended for cephalopod feeding

Abstract

In this study, HPTLC was used to make a quantitative analysis of the total lipid content (TL dry weight) and their classes in 39 samples, including molluscs, crustaceans, fish and meals in an attempt to identify those most suitable for formulating diets for cephalopods by reference to an index of nutritional quality (OILC: Oser's index modified for lipid classes). All the crustaceans analysed (< 10% TL), fish from artisanal fisheries such as Boops boops, Gadus poutassou, Mugil sp. and Gadus minutus (< 10% TL) and the plant meals (TL < 5%) would cause fewer digestive problems than the fish that were a by-catch from fish farms (B. boops or Sparus aurata), pelagic species (Sardina pilchardus or Trachurus trachurus) or krill meal, which are characterised by their high lipid content (20-60% TL). These latter feeds were associated with neutral lipids, mainly triglycerides during the summer. Mytilus galloprovincialis, Carcinus maenas, G. poutassou, Mugil sp., S. pilchardus and G. minutus had a more appropriate lipid content and profile during the winter, when they showed a higher OILC due to the greater variety of polar lipid classes they contained. Phospholipids like PS, PI and PE seem to be limiting nutrients in cephalopods because of their high content (78-542, 41-309 and 152-2,114 mg/100 g, respectively) compared with the rest of the samples. None of the meals analysed showed a good nutritional balance per se and should only be used in conjunction with other foods.