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Keywords:

  • astacid crayfish;
  • juvenile rearing;
  • Pacifastacus leniusculus ;
  • practical diet;
  • vitamin C

Abstract

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.