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The aim of this study was compare the results obtained after testing new spawning agents (Ovaprim and PG-600) in artificial reproduction of common tench in comparison to Ovopel, the spawning agent, which worked very well in this species. The tench spawners were collected from open waters. After catching, the selected fish were transported to the hatchery, where the fish were treated with the spawning agents: Ovopel at 1 pellet kg⁻¹ Ovaprim at 0.5 ml kg⁻¹ or PG-600 at 600 IU kg⁻¹. The fish from the control group received saline (0.9% NaCl). The best parameters recorded during the artificial reproduction, such as the percentage of ovulated females and embryo survival at the eyed-egg-stage were obtained in the group treated with GnRH analogues. In general, the obtained results indicate that all of the tested spawning agents might be used on successful tench artificial reproduction. However, after application of Ovopel better results were recorded.
The aim of this study was to define an influence of water temperature on successful reproduction of burbot under the hatchery conditions. Research was conducted during four successive spawning seasons where wild spawners were used. In the first three years of study fish were kept in three different (natural) thermal conditions. In the fourth year it was confirmed that the highest efficacy of synchronization of the spawning could be reached only under controlled thermal regimes. That year one group of spawners was kept at 6℃ before spawning and then a sudden decrease of the temperature to 1℃ was applied. Restrictively controlled thermal regime during reproduction of burbot in captivity caused the most synchronous spawning of females (2 days-period) in contrast to control group (17 days-period) and even hormonally stimulated (4 days-period). Eggs survival in thermally manipulated group was very high (over 85% in the eyed-egg-stage). This research proved that manipulation of water temperature is the most important technique which should be applied in controlled reproduction of burbot and it is suggested that the temperature is the major factor during final maturation of burbot females. Also, confirmed the fact that incubation of burbot eggs in temperature over 5℃ causes its high mortality (100% in the eyed-egg-stage).
Artificial reproduction of asp under controlled conditions was done using two different spawning agents based on GnRH analogues and dopamine antagonists (Ovopel and Ovaprim). Fish in the Ovopel and Ovaprim and combined treatment groups were treated with a dose equivalent to 1.2 pellets (0.2 and 1.0), 0.5 cm³ liquid (0.1 and 0.4) and 0.2 pellets and 0.4 cm³ liquid per kg of body weight respectively. The highest percentage of ovulation (100%) and embryo-survival to the eyed-egg-stage (81.3%) was recorded after the application of a combination of Ovopel and Ovaprim in comparison with other groups. Fish from the control group did not ovulate. The latency time was shorter in the groups where Ovopel and Ovopel with Ovaprim was applied (40) than in Ovaprim group (42–44 hrs). The obtained results indicates that combination of Ovopel with Ovaprim might be successfully used for artificial reproduction of asp.
A preliminary examination was carried out into the effect that various activating liquids have on the survivability of ide Leuciscus idus (L.) embryos. It was found to be similar (54–59%) in four study groups; the embryo survivability was found to have decreased (44%) only in the group where non-sterilised tap water was used for gamete activation. A negative correlation was found between water conductivity, salinity and sperm motility. A positive correlation was found between water conductivity, salinity and embryo survivability. A negative correlation between the sperm motility and the survivability of ide embryos at the eyed-egg stage shows that the fertilisation result is more affected by the duration of sperm movement than by the percentage of motile sperm.
Background. Obtaining the appropriate quantity of milt and spermatozoa of biologically good quality depends on a number of environmental factors. Additional factors may be involved while using a hormonal stimulation. The aim of this study was to analyse the effect of time, after stimulation with Ovopel [(D-Ala6, Pro9-NEt)-mGnRH+metoclopramide] (1 granule∙kg-1 body weight) on semen quality indicators of common carp, Cyprinus carpio L., over the period of 72 h post injection. Materials and methods. The total volume of milt (TVM, mL), volume of milt per 1 kg of the male body weight (VOM, mL∙kg-1 b.w.), total sperm production (TSP, ×109), and their concentration (×109 mL-1) in milt were determined. Additionally, the motility of spermatozoa (%) by means of the subjective method and the osmotic pressure of seminal plasma (mOsm∙kg-1) were determined. The milt was collected 24 h (group I, n = 10), 48 h (group II, n = 10), and 72 h (group III, n = 10) after stimulation with Ovopel. Results. No significant differences (P > 0.05) in the main parameters of milt i.e., the motility and concentration of spermatozoa in the milt, as well as in the osmotic pressure of seminal plasma were found between the experimental groups of the fish. Higher TSP and VOM values were recorded 24 h after Ovopel injection compared to samples obtained after 72 h (P <0.01 and P < 0.05, respectively) and 48 h (P > 0.05). TVM values were also higher at 24 h after the injection than those noted at 48 and 72 h (P < 0.01). Conclusion. The lack of significant differences in the motility and concentration of spermatozoa in milt at 24, 48, and 72 h after injection indicate that time after Ovopel administration does not have an influence on the main indicators of common carp milt quality. However, we noted significant differences in TSP, TVM, and VOM between samples obtaining 24 h and 72 h after hormonal stimulation. The highest quantity indicators i.e., the number of spermatozoa in milt and volume of obtained milt noted for samples obtained after 24 h suggest that this time is better for milt sampling than time after 48 and 72 h.
A study on reproduction of neon tetra has been carried out under controlled conditions. Neon tetra is very popular aquarium fish. It was observed that spawners of this species produce viable gametes during a few (5–6) spawning periods only. From the breeding perspective fish of that species should be reproduced again shortly after the completed spawning and time between spawns should be 15 to 20 days. Keeping the fish between spawning periods more than 20 days results in a significant deterioration of quality of gametes, expressed by the decreased number of 12-day-old larvae. It was shown that before spawning spawners should be kept in water at 22℃. The negative effect of keeping the reproducers in water at 25℃ accumulated with time.
Milt was collected from the tench Tinca tinca (L.) following hormonal stimulation with carp pituitary homogenate (CPH, group I, n = 9), Ovopel (group II, n = 8) and Ovaprim (group III, n = 9). Males non-stimulated fish were used as a control (group IV, n = 6). The parameters determined included the total volume of milt (TVM, ml) and the volume per kg of the males’ body weight (VOM, ml kg⁻¹ b.w.), total number of spermatozoa produced by the males (TSP, ×10⁹) and the number of spermatozoa per kg of their body weight (TNS, ×10⁹ kg⁻¹ b.w.). Moreover, attempts were made to show the effect of the hormone preparations on spermatozoa motility (%), their concentration in milt (×10⁹ ml⁻¹) and the total protein content in seminal plasma (mg ml⁻¹). Osmotic pressure of the seminal plasma (mOsm kg⁻¹) was determined to check if the milt samples were contaminated with urine. Pearson’s linear correlation was also determined between the osmolality, on the one hand, and the spermatozoa motility and concentration of spermatozoa in milt of the groups examined in the study, on the other. The significance of differences between the analysed parameters was checked with Tukey’s test (One-way ANOVA, α = 0.05). Motility and concentration of spermatozoa in the remained relatively low, not exceeding 22% and 5.0 · 10⁹ ml⁻¹ in each of the groups. Using CPH, Ovopel or Ovaprim did not result in any significant increase (P > 0.05) in the amount of milt obtained (TVM, VOM) or the total amount of spermatozoa produced as compared to the control group. Significant differences (P < 0.05) were found only between the TNS values for group I (CPH), and group IV (control). Osmolality of the seminal plasma did not exceed 120 mOsm kg⁻¹ in any of the groups under examination. Its low values as well as low motility and low concentration of spermatozoa in milt indicate that milt was contaminated with urine, which is also corroborated by a significant correlation between osmolality and motility of spermatozoa in group III (R² = 0.828; P < 0.001) and IV (R² = 0.983; P < 0.001) and between osmolality and concentration of spermatozoa in each of the groups (R² = 0.447; P < 0.05, group I; R² = 0.964; P < 0.001, group II; R² = 0.768; P < 0.001, group III and R² = 0.924; P < 0.001; group IV).
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