Utilization of water cress (Nasturtium officinale L.) in noble crayfish (Astacus astacus) feeding

Juvenile Astacus astacus (initial b.w.: 0.98 +/- 0.06 g) were cultured (30 crayfish/m(2)) in 2001 tanks for 69 days. The experimental design was composed of three treatments as follows: control diet (C) (crude protein: 28.4% of the total dried matter, "DM"; ether extract: 6.22% DM), water cress (W) (crude protein: 20.7% DM; ether extract: 1.9% DIVI) and control diet + water cress (C + W) with thee replicates per treatment. Relative growth rate improved significantly (P < 0.05) in crayfish fed C + W (+ 110%) compared to W (+ 43%) and the control diet (+ 36%). Gross protein and lipid retentions of the treatment C + W were significantly higher than the control diet and water cress fed alone. At the end of the experiment, a higher survival rate of A. astacus was observed (P < 0.05) in the treatment C + W (67%) and C (71%) compared to the W (58%). These results suggest that the plant water cress (Nasturtium officinale) can be used as supplemental food in noble crayfish feeding.