Melatonin’in Tatlısu İstakozu (Pontastacus Leptodactylus Eschscholtz, 1823) Yavrularında Gelişim, Hayatta Kalma Orani ve Bağışıklık Sistemi Üzerindeki Etkisi

: The aim of this study was to investigate the effects of melatonin on growth, survival and immune response (total hemocyte counts) of Pontastacus leptodactylus juveniles (stage II-IV). With this aim, five separate groups with 4 replicates were formed by adding melatonin at the doses of 0, 0.5, 1, 2, 4 mg/kg to the trial feed. The experiments was conducted using stage II P. leptodactylus juveniles which fed for 60 days. During the experiments, a 50% water change once a day and continuous ventilation was provided. Stock density was determined as 20 juveniles for each replicate tank. The juveniles were fed at rate of 5% of their body weight once a day. The average initial weight and total length of juveniles were 34 ± 4 mg and 11.6 ± 0.4 mm, repectively. At the end of the experiment, the maximum average total length (22.0 ± 3.6 mm) was in the group fed with 2 mg/kg melatonin containing diet, the best average live weight (216 ± 116 mg) was in the group fed with 4 mg/kg melatonin containing diet, the highest survival rate (44.4 ± 13.9%) was in the 2 mg/kg melatonin group and the highest average total hemocyte count (2.27 ± 0.49 x 10 6 cells/ml) was in the 2 mg/kg melatonin group. However, the differences between the groups were not statistically significant (p > 0.05). As a result of this study, it was determined that feeding with melatonin supplemented feed have no significant effect on growth, survival and immune response of P. leptodactylus juveniles.