Phospholipid composition of common carp ( Cyprinus carpio) larvae starved or fed different phospholipid classes

Abstract

Following earlier experiments, which showed important differences in early development of common carp larvae dependent on the phospholipid (PL) class composition of the diet, the present study evaluated the hypothesis that the manipulation of the dietary PL might have modified the PL composition of the larvae. For this purpose, we examined the fatty acid (FA) composition of body phosphatidylcholine (PC), the body PL content and the PL class profile in carp fed from first-feeding up to 28 days semi-purified diets containing different PL classes. Larvae kept for 1 to 7 days without food were analyzed for comparison. The FA distribution in the larval body PC between saturated/monounsaturated/polyunsaturated FA (SAFA/MUFA/PUFA) varied according to larval size and diet, being approximately 40/30/30 in unfed larvae and 33–35/38–44/22–28 in fish after 28 days of feeding. The greatest modification concerned the relative importance of n−3 and n−6 FA, with n−3/ n−6 ratios changing from approximately eight in the start-feeding larvae to 0.04–0.11 in the final fed larvae, in accordance with the low dietary n−3/ n−6 ratios (0.02–0.08). The total PL content (% dry matter) of the fed larvae fluctuated around 7%, irrespective of fish size or diet. Expressed as a percentage of total PL, PC increased and phosphatidylserine (PS) decreased during growth, whereas phosphatidylethanolamine (PE), phosphatidylinositol (PI) and phosphatidic acid (PA) remained constant. No significant effect of the PL class composition of the diet on that of the fish was found. The fixed PL class composition of the larvae, of a given size, implies the synthesis of the PL classes which are not provided by the diet. It is suggested that this synthesis is a limiting factor for the development of early larvae fed PL-deficient diets.