Spawning induction in Kutum, Rutilus frisii kutum (Kamensky), with different hormones: Analysis of hormone profiles and induced spawning success

The objective of this study was to evaluate the effectiveness of different hormones on spawning success and sex steroid changes in Caspian Kutum, Rutilus frisii kutum. Groups of five fish were injected intramuscularly as follows: 2 mg kg^-1 common carp pituitary extract (CPE) as the positive control, 100 IU kg^-1 human chorionic gonadotropin (hCG), 2 μg kg^-1 luteinizing hormone releasing hormone analog (LHRHa2), 10 μg kg^-1 synthetic analogue gonadoliberins (sGnRHa), 0.2 mL kg^-1 Ovaprim which is a complex of salmon GnRH analogue with a dopamine receptor antagonist (domperidone), a combination of 2 μg kg^-1 LHRHa₂ and 100 IU kg^-1 hCG, a complex of 10 μg kg^-1 sGnRHa and 100 hCG IU kg^-1, and saline solution as the negative control. Blood samples were taken simultaneously with injections and after ovulation. The results showed that no fish ovulated in the negative control group. In the CPE treatment group, 4 of 5 fish ovulated. In the other experimental groups; no response was observed in the hCG group, while the females injected with sGnRHa-alone, LHRHa₂-alone, and sGnRH+hCG had low spawning percentages. Of the hormones tested, the combination of sGnRHa+domperidone was the most effective spawning inducer and the greatest spawning success was obtained. Significant decreases after injection were observed in plasma concentrations of 17α estradiol, 17β-hydroxy progesterone, and progesterone in all treatments, while plasma testosterone concentrations increased significantly. This study revealed that a combined sGnRHa and dopamine antagonist can improve the effectiveness of artificial reproduction of Kutum. Since the combination of sGnRHa and domperidone is purer than CPE and has the most effective in inducing ovulation, it is preferred for inducing spawning in this species.