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Optimalizace procesu triploidizace u candáta obecného (Sander lucioperca)
TRNKA, Kamil
This thesis was aimed on optimization of induction of triploidization of pikeperch (Sander lucioperca) using cold, hot and pressure shocks. To induce the triploid status of the larvae using cold shock fertilized eggs of pikeperch were dropped into the cold bath of temperature 0,5-1°C in 2, 4, 8, 12 and 16 minutes post fertilization with shock duration of 20, 40, 60, 90 and 120 minutes. Hot shock was induced by 30°C bath 2, 4, 8, 12 and 16 minutes post fertilization with duration of shock 5, 10, 20, 30 and 40 minutes. Pressure shock was also tested for induction of triploidization using pressure of 70 MPa 5, 10 and 20 minutes post fertilization with duration of shock 5 minutes. Ploidy level was then determineted using flow cytometry. As a result hatchability (%), share of malformed larvae (%), share of triploid individuals (%) and yield of triploids (%) were determined. None of the experiemental shocks have led to a 100% share of triploids concerning the samples examined by flow cytometry. Best result was reached via pressure shock with duration of 20minutes which resulted with share of triploid individuals of 95% and yield of triploids 12.2+-2.5%. It must be noticed that increasing duration of pressure shock resulted in decreased hatchability and increased share of malformed larvae. Second best result was achieved via cold shock. Worst results were obtained via hot shock.
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Vliv hustoty obsádek sumečka afrického (Clarias gariepinus) na efektivitu jeho intenzivního chovu v recirkulačním akvakulturním systému
TRNKA, Kamil
This study is a dressing the breeding process of the african catfish kept in RAS recycling waste heat from the biogas plant. The weight, SGR, FCR, FC, survival rate and were evaluated. During the first test different breeding densities were established (30, 60, 90, 120 kg.m-3) and fishes were kept in the tanks without lowering the the density to the original. Into the tanks with the same quality of the water, we introduced juveniles of the african catfish. Results of the first test showed that the best growth of the african catfish is achieved in the breeding density up to 230 kg.m-3. In the second experiment, the different breeding densities were established (90, 120, 150 a 180 kg.m-3). These densities were periodically lowered to the starting density each Month. In this test we achieved higher SGR and lower FCR. There were no significant differences among the density's groups. Third test was based on the presence of the sorting of the fish in tanks. While not sorting negative influence has appeared. In the non-sorted group, we found couple of marked-sized fish and couple of bellow average fish. Also, the growth parameters showed better results in the sorted group. All experiments showed that the best breeding density is from 180 up to 230 kg.m-3.
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