Effect of dietary supplementation of calcium chloride on growth, survival, moulting frequency and body composition of narrow-clawed crayfish, Astacus leptodactylus (Eschscholtz, 1823)

摘要

The effects of dietary calcium chloride (CaCl2) concentration on the growth, survival, moulting and body composition of Astacus leptodactylus were studied. Diets were prepared using supplementation of 0 (control), 30, 60 and 120 g kg(-1) calcium chloride commercial trout larvae diet containing 50% protein and 12% lipid. Astacus leptodactylus larvae with an average total length of 22.0 +/- 0.05 mm (TL) and weight of 0.53 +/- 0.01 g obtained from eighteen ovigerous females collected from Seydisehir Sugla Dam lake in Konya, Turkey, were stocked in 0.2-m(2) aquariums at a rate of 50 crayfish m(-2) and reared for 90 days. The experiments included four treatments (diets) with three replicates each. Calcium chloride exerted positive effects on growth, moulting frequency, feed efficiency and survival of narrow-clawed crayfish. Crayfish fed with 60 g calcium kg(-1) calcium chloride-supplemented diet exhibited the highest weight gain and specific growth rate (SGR) but the lowest survival rate (63.3%) (P 0.05). There were no significant differences (P > 0.05) in mean moisture (803.5 g kg(-1)) and protein content (177.0 g kg(-1)) in crayfish tail meat. However, lipid values were between 3.8 and 11.6 g kg(-1) and significantly different among the diets (P 0.05). Diet with 60 g kg(-1) calcium chloride is recommended for the best growth of freshwater crayfish.