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The objective of the present study was to investigate the effect of dietary phospholipid (PL) level on growth and feed intake of juvenile amberjack ( Seriola dumerili) fed non-fishmeal (non-FM) diet containing alternative protein sources; soybean protein isolate, tuna muscle by-product powder and krill meal. Three non-FM diets were prepared to contain three levels (14, 37 and 54 g kg−1 dry diet) of PL (soybean lecithin acetone insoluble, 886 g kg−1) and growth performance was monitored in a 30-day growth trial by using 2.6 g of fish. The results indicated that final body weight, weight gain and feed intake significantly increased with increasing dietary PL level. At the highest dietary PL level (54 g kg−1 dry diet), the fish consumed 14.8% and 10.2% as much feed as those fish fed diets containing 14 g kg−1 dry diet and 37 g kg−1 dry diet PL, respectively. An increasing tendency with increasing dietary PL level on feed efficiency was observed. In conclusion, the present study demonstrated that dietary PL supplementation could increase feed intake, and improve the growth of juvenile S. dumerili fed non-FM diets. Therefore, purified PL might be a good candidate to stimulate the growth of fish through enhancing the feed intake when they are fed diets containing alternative protein sources. [ABSTRACT FROM AUTHOR]

A feeding experiment was conducted to examine the efficacy of a vitamin C (L-ascorbic acid, AsA) derivative,l-ascorbyl-2-monophosphate Na/Ca (AMP-Na/Ca) by comparing tol-ascorbyl-2-monophosphate-Mg (AMP-Mg) in terms of growth, AsA content in tissues, and hematology in yellowtail Seriola quinqueradiata juvenile (1.10 ± 0.01 g). Furthermore, a stress resistance test for the species fed AMP-Na/Ca was also conducted. In experiment 1, 11 test pellet diets with different levels of AMP-Na/Ca (0, 12, 43, 88, 440 and 881 mg AsA kg−1diet) and AMP-Mg (0, 16, 52, 106, 595 and 1164 mg AsA kg−1 diet) were formulated and fed to the yellowtail three times per day for 50 days. In both the vitamin C sources, the survival rates of the fish fed diets without supplemental AsA were lower than 50% at day 20, and more than 50% mortality occurred in fish that fed the diets containing 12 or 16 mg AsA kg−1 after day 30. However, no significant differences were detected in survival and growth among fish that fed the diets containing more than 43 mg AsA kg−1. Liver and brain AsA concentrations generally increased with increasing dietary AsA level in both sources. In experiment 2, test diets were formulated to contain 43, 88, 440 and 881 mg AsA kg−1 using AMP-Na/Ca, and after 60 days of feeding, yellowtail juveniles were subjected to low salinity and air exposure stress. The fish that received diets with 440 mg AsA kg−1 showed significantly higher tolerance to low salinity stress and higher survival rate in air exposure stress than those of other groups. The present study demonstrated that yellowtail juveniles could utilize AMP-Na/Ca as an AsA source like AMP-Mg, and that supplementation of 43–52 mg AsA kg−1 diet was optimum for normal growth. However, this study showed that dietary inclusion of 440 mg AsA kg−1 would be necessary to improve stress resistance of this species. [ABSTRACT FROM AUTHOR]