The effect of different levels and sources of dietary phosphatidylcholine on the growth, survival, stress resistance, and fatty acid composition of postlarval <i>Penaeus vannamei</i>

The effect of dietary purified phosphatidylcholine (PC) was evaluated on growth, survival, resistance to osmotic shock, and fatty acid composition of early postlarval Penaeus vannamei (0.3 mg initial dry weight) fed semi-purified diets. PC sources used were purified soybean PC (SPC, 95% purity), chicken-egg PC (ECP, 94% purity), and de-oiled soybean lecithin (DSL, 23% PC). The growth response of shrimp fed 1.5% of SPC or 6.5% of DSL was significantly greater than that of shrimp fed a PC-deficient diet, whereas no effect was observed either on survival or stress resistance. Further increasing the dietary level of soybean PC from 1.5% to 3.3% resulted in a significant decrease of the shrimp weight gain. Shrimp receiving 1.5% of PC, provided either as chicken-egg PC, soybean PC, or de-oiled soybean lecithin did not show differences in growth, but had a significantly greater weight gain than that of the shrimp fed 1.5% of the de-oiled soybean lecithin, which indicated that the phospholipids in lecithin other than PC cannot compensate for a PC deficiency in the diet. With increasing dietary level of soybean PC, significantly higher levels of 20:1n-9, total n-6 polyunsaturated fatty acid (PUFA), and 20:5n-3 were present in the total lipids of shrimp, whereas the proportionate levels of 18:1n-9 and total monenes significantly decreased