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Influence of feeding management on intensive breeding of pikeperch (Sander lucoperca)
KUČERA, Václav
This thesis is aimed on problematics of intensive pikeperch aquaculture and the influence of the feeding by different types of pellets and also different frequencies of feeding during the day. Whole thesis consists of two separate experiments. In the first experiment I tried to evaluate the influence of sinking and floating type of pellets on the growth abilities and production markers of juvenile pikeperch. First experiment was stocked with 8000 pcs of juvenile pikeperch (average weight 21,38g). These fish were kept in controlled conditions for 16 weeks (average temperature of 21,37 ? 0,66 °C (7:00) and 20,77 ? 0,55 °C (15:00), average dissolved oxygen levels of 127,43 ? 2,37 % (7:00) and 117,03 ? 1,14% (15:00) °C, 120 % and initial biomass of 13,42 kg/m?). These fish were fed by belt feeders two types of pellets (floating Skretting Europa and sinking Biomar Effico Sigma) with the same nutrient composition. After 16 weeks all the production markers (SGR, FCR, WG, TL, CF and survival) were examined. Almost all the parameters showed the statistically significant difference in favor of the sinking pellets. Although growth heterogenity turned out to be lower in the group fed by floating pellets. In the second experiment 600 individuals of juvenile pikeperch with average weight of 37,49 g were stocked in tanks. These fish were kept in controlled conditions for 6 weeks (average temperature of 21,37 ? 0,66 °C (7:00) and 20,96 ? 0,66 °C (15:00), average dissolved oxygen levels of 127,43 ? 2,37 % (7:00) and 117,03 ? 1,14 % (15:00) with initial biomass of 13,35 kg/m?). These fish were fed by automatic feeder Imetronic Self Feeder in 3 different frequencies a day (3,6 or 12 batches). Pellets Skretting Europa- 15F were used in this experiment. After 6 weeks of rearing production markers were examined. Growth heterogenity, somatic indexes, and fin erosion were also examined. Also, blood samples were taken. After data analysis no statistically significant difference was found among the production markers in all three groups. Growth heterogenity was proven to be the lowest in the group fed 3x a day and highest in the group fed 12x a day. Organosomatic indexes showed statistically significant difference of HSI (hepatosomatic index). Highest index was observed in group fed 3x a day. During the analysis of the data from biochemical analysis increased levels of albumins and tryglicerids were observed especially in the group fed 12x a day. Simultaneously, statistically significant differences among the amonia levels (lowest concentration in the group fed 3x a day and highest in group fed 12x a day) and glucose (lowest concentration in the group fed 3x a day, two other groups had almost the same level of glucose) levels in plasma were found. As a group with the best results was determined a group fed 6x a day. This group reached satisfying results in production markers (better than group fed 3x a day but slightly worse than group fed 12x a day). Also, lower growth heterogenity than in group fed 12x a day was observed. Group fed 6x a day also displayed the best working lipid metabolism in contrary to the group fed 12x a day which displayed the disorder of the lipid metabolism. Also, the fin erosion was slightly lower than in a group fed 12x a day.
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