ESSENTIALITY OF DIETARY PHOSPHOLIPIDS FOR CARP (CYPRINUS-CARPIO L.) LARVAE

Two experiments were carried out in order to evaluate the essentiality of phospholipid (PL) addition to semi-purified diets for first-feedin g carp larvae. In Experiment I (25 days), a casein-based diet was supp lemented with 0, 2 or 4% of a purified PL source (PL level in source: 98%) and with 0 or 4% of peanut oil (PO). One casein-based diet withou t PL was supplemented with choline chloride. In Experiment II (21 days ), the same casein-based diet was supplemented with 7 commercial or ex perimental PL sources (PL content in sources: 55-81%). Sources include d soybean PL, lyse soybean PL, obtained by treatment with phospholipas e A(2), and soybean PL with Ca2+ added in order to decrease the oil/wa ter (O/W) emulsifying properties. Diets were made isolipidic by adding PO. One diet was formulated to be PL-free. In both experiments, all s emi-purified diets supplemented with PL significantly improved surviva l and growth of carp larvae in comparison with PL-deficient diets. Res ults indicate that the beneficial effect of PL was not due to the corr ection of a choline deficiency or to the correction of an essential fa tty acid deficiency and thus supported the idea of the essentiality of the PL entity for the early nutrition of larvae. The effect of PL see med unrelated to their emulsifying properties as larval performances w ere not affected by Ca2+ enrichment while they were decreased by lyso- PL supplementation. It is presumed that the PL requirement for membran e building and renewal could be especially high during the fast growin g larval stages and could exceed the endogenous ability of PL synthesi s. Attention should be paid to an adequate dietary PL supply when larv ae are offered artificial diets instead of PL-rich live food.