Comparison of different soybean phospholipidic fractions as dietary supplements for common carp, Cyprinus carpio, larvae

Abstract

Two experiments were conducted in order to compare the effects of several phospholipid (PL) sources prepared from soybean lecithin on growth and survival of start-feeding carp larvae. Eight diets were tested in each experiment. All diets contained 94% of the same casein–dextrin mixture and 6% of added lipid, consisting of peanut oil alone or supplemented with a PL source. In both experiments, diets supplemented with fractions enriched in phosphatidylinositol (PI) resulted in the highest survival (95% after 25 and 31 days, respectively). Addition of phosphatidylcholine (PC) allowed high initial growth rates during the first week of feeding, similar to or higher than those obtained with PI, but induced a peak of mortality afterwards and, in the first experiment, a high frequency of deformed fish. Larvae fed PC-enriched diets started to die at a larger size than larvae fed PL-deficient diets. Other tested fractions with phosphatidylethanolamine, phosphatidylserine or phosphatidic acid as the major PL class resulted in intermediate results between those given by PI- and PC-rich fractions. Dietary hydrogenated soybean PC resulted in a decreased growth compared to native soybean PC. Soybean lysolecithin was inferior to original lecithin for final larval growth and survival, but was superior to peanut oil without PL. Present results confirm that both the polar head group and the fatty acid composition of the dietary PL may affect their nutritional value for larval carp and suggest distinct requirements for PI and PC.