Effects of vitamin C inclusion in practical diets on survival and growth of juvenile crayfish ( Pacifastacus leniusculus Dana, Astacidae) from the onset of exogenous feeding.

The aim of this study was to evaluate the effects of practical diets with different levels of vitamin C on survival and growth of juvenile crayfish ( Pacifastacus leniusculus). An 80-day trial was conducted with stage 2 juveniles from the onset of exogenous feeding. Four practical diets differing in the content of l-ascorbyl-2-monophosphate- Na were prepared: 0, 0.2, 0.4 or 0.8 g kg−1 diet. Each diet was tested on grouped or individually isolated crayfish. Diets had no significant effects on survival of crayfish held in groups (average: 73.1%) neither on the isolated ones (average: 90%). Crayfish fed the diet with 0.2 g kg−1 of l-ascorbyl-2-monophosphate- Na had the highest growth (groups: 13.64 mm carapace length ( CL), 542.4 mg weight; isolated: 17.05 mm CL, 1213.2 mg weight) and the lowest feed conversion ratio (average of grouped and isolated: 0.99). This study provides the first data on vitamin C requirements of freshwater crayfish. A level of 0.2 g l-ascorbyl-2-monophosphate- Na kg−1 diet (0.07 g ascorbic acid equivalent) can be recommended for juvenile P. leniusculus during the first period of intensive rearing. [ABSTRACT FROM AUTHOR]