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The comparison of out-off-season spawning of two cultured ide stock were examined. The obtained results show, that is possible to reproduced ide a few months before their natural spawning season. Generally, the percentage of spermiation and ovulation was very high, as well as spawners survival. The biological quality of the gametes was higher in stock cultured at ponds, than from fish cultured under controlled conditions. One ide females from cultured stock under controlled conditions ovulated without hormonal stimulation (control group). The quality of oocytes collected from this fish was much lower than from hormonally stimulated fish.
Ide spermatozoa were genetically inactivated using ultraviolet (UV) irradiation. The highest survival of haploid embryos was noted in the group treated with UV for 5 min (dose 1920 J m-2). High-temperature shock influenced the suppression of the second polar body in ide oocytes. The highest survival rate of diploid gynogenotes (below 10%) was observed in groups shocked at 12 min after egg insemination for 3 min. Eggs shocked later in time exhibited lower survival rates.
Bream, Abramis brama (L.), eggs fertilized with genetically inactivated sperm (UV irradiation dose of 1920 J m-2) were exposed to thermal cold shock to produce meiotic gynogenotes. The shock was applied at one-minute intervals from 1 to 10 min after egg insemination. The temperature of the shock was 2.0 ± 0.1°C, and its duration was 45 min. The water temperature prior to the shock was 20.0°C. Eggs fertilized with genetically inactivated sperm (putative haploids) exhibited retarded and abnormal development. The yield of gynogenesis was relatively low, except for the group to which the shock was applied 1 min after fertilization (about 30% in comparison with the controls). Ninety fish from the control and gynogenetic groups were reared for ten months. The survival of the gynogenetic bream was twofold lower than that of the controls. The gynogenotes were highly variable in size and exhibited some morphological abnormalities. The sex ratios in the control groups were close to 1:1, whereas all the gynogenotes were female.
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