Vitamin C requirement of kuruma shrimp postlarvae,Marsupenaeus japonicus(Bate), usingl-ascorbyl-2-monophosphate-Na/Ca.

l-ascorbyl-2-monophosphate-Na/Ca (AMP-Na/Ca) was used as a vitamin C source to investigate the ascorbic acid (AsA) requirements on growth performance and stress resistance of the post-larval kuruma shrimp,Marsupenaeus japonicus. Purified carrageenan-microbound diets with six levels of AMP-Na/Ca, AsA equivalent to 0, 20, 56, 87, 759 and 1697 mg kg⁻¹ diet were fed to triplicate groups ofM. japonicus(mean initial weight 16±0.3 mg) for 30 days. The diets with AsA 0, 20 and 56 mg kg⁻¹ showed high cumulative mortality after 10 days of feeding. After the 30-day trial, the shrimp fed these diets had significantly lower survival and weight gain (WG, %) than those fed the 87, 759 and 1697 mg AsA kg⁻¹ diets. Specific growth rate and individual dry weight showed the same pattern as WG (%). There were no significant differences in growth performance among the groups fed the AsA levels at 87, 759 and 1697 mg kg⁻¹ at the termination of feeding trial. Broken-line regression analysis indicated that 91.8 mg AsA kg⁻¹ in the diet was the optimum for post-larval shrimp. On the other hand, dietary level of more than 800 mg AsA kg⁻¹ was needed to ensure high resistance to stressful conditions such as osmotic and formalin stressors. [ABSTRACT FROM AUTHOR]