The Effects of Diets with Different Protein Levels on Growth, Survival and Body Composition of Juvenile Freshwater Crayfish (Astacus leptodactylus Eschscholtz, 1823)

The effect of three different dietary protein contents were evaluated on growth, survival and body composition of newly hatched third instars astacus leptodactylus juvenile and to determine food preference for intensive culture system of this species. the experiment consists of three treatments (diets). the diets were: 1) commercial trout feed consist of 55% protein (ctf), 2) commercial carp feed consist of 35% protein (ccf) and 3) fresh fish meat consist of 18% protein (ffm). thirty newly hatched third instarts of astacus leptodactylus (mean weight 44.5 ± 3.4 mg and mean total length 10.8 ± 0.4 mm) were randomly stocked in nine aquariums in 25 l (area: 0.2 m^2), for 90 days at 28°c. the experimental desing was conducted 3 treatment and with 3 replicates. the result of experiment indicated that final weight and length varied among diet groups were 0.38 ± 0.03 g, 0.30 ± 0.04 g, 0.32 ± 0.04 g and 29.41 ± 0.5 mm, 27.43 ± 0.4 mm, 27.93 ± 0.6 mm respectively. the highest mean growth was observed from the group of crayfish feed ctf. the survival of crayfish was similar for three diets. the highest survival rate 81.85% was observed in ffm. the highest specific growth rate (sgr) in ctf (0.01/d) was obtained at the end of the experiment. feed conversion rates were found similar for all treatment groups, wherease molting frequencies were different among the diets (p<0.05). the highest molting frequency were observed in ctf and followed by ffm and ccf feeding groups, respectively. at the end of the feeding period, protein, hepatopancreas moisture, and lipid values were found similar for all of the experimental groups (p>0.05). the results indicated that ctf alone could provide better growth, molting frequency, and yield in comparison to other diet groups, but survival was the in ffm diet group.