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Vliv alternativních zdrojů bílkovin v rybím krmivu na růst ryb a rostlin ve dvousmyčkovém akvaponickém systému
NIKL, Ondřej
The objective of this thesis was to evaluate the production efficiency of feeds which were designed with the intention of developing a special aquaponic feed. Further, to evaluate the content of nutrients in water, sludge and nutrient solutions and their influence on plant growth and finally suggest possible modifications to the feed composition. Aquaponic feed should respect nutritional requirements of fishes and plants, not put burden on the environment by not used nutrients and with regards to sustainability, use alternative sources of protein instead of marine fish meal. Because of that, three experimental isoprotein and isocaloric feeds were proposed. Feed A contained conventional ingredients including marine fish meal. Feed B used freshwater fish meal and exclusively plant proteins not regarding its origin. Feed C was made of sustainable and local sources of protein. The experiment was conducted in the aquaponic hall of Faculty of Fisheries and Protection of Waters, University of South Bohemia. As experimental material was used Nile tilapia (Oreochromis niloticus) and lettuce (Lactuca sativa). Feed B shown similar values of all production indicators as conventional feed A. Weight of fishes in system A after thirteen weeks increased by 143,68 % and in system B by 136,56 %. Weight of fishes in system B was at the end of experiment inconclusively lower by 4,08 %. Feed conversion ratio (FCR) of feed B (1,92?0,10) was inconclusively higher by 8,47 % against FCR of feed A (1,77?0,13). Average weight of aerial parts of plants growing in nutrient solution created from mineralized sludge gathered from system B, supplemented with missing nutrients reached value 221,8?33,9 g after four weeks. That was inconclusively more by 44,21 % than average weight of plants grown in special hydroponic solution and by 8,62 % more than weight of plants grown in enriched solution gathered from system A. Experimentally it was proven that in aquaponic feeds it is possible to substitute marine fish meal by alternative source of protein and using these feeds ensure an effective nutrition for fish and plants in a two-loop aquaponic system.
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