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Vliv původu a strategie chovu na nutriční hodnotu produkovaných lososovitých ryb.
Trybulovský, Filip
In my work, I was dealing with the influence of the origin and strategies of breeding of produced salmonid fish on the nutrition value of the muscle. Rainbow trout, brook trout and interspecific hybrid of Salvelinus alpinus and S. fontinalis were analyzed. Two feed tests were performed. Both tests were carried out in an experimental recirculating system at the Department of Fisheries and Hydrobiology at the Mendel University in Brno. Length-weight parameters of fish were measured, from which individual indices, production and conditional parameters were subsequently calculated. In addition, the yield and viscerosomatic index were determined. The content of fat, proteins and dry matter of the fish muscle was determined and used for nutrition value evaluation. The effect of reduced oxygen saturation (below 70 %) compared to normal oxygen saturation (around 100 %) was also analyzed in the first test. In Test 1, feedstuff Biomar Efico Enviro 920, Focus Plus with the addition of immunostimulants and Advance with a higher proportion of plant components were used. No statistically significant differences in production and conditional parameters, length-weight ratios and yields were registered for these feeds. The highest percentage of fat content in the muscle (7.66 %) was in fish fed Focus Plus. The dry matter and protein content of the muscle was similar. The greatest effect of reduced O2 was noticed in the fat content of the muscle. For a group of fish fed Efico Enviro 920, it was statistically significant (p = 0.03 and 0.042). Yield values were higher in a group with reduced oxygen saturation. This could be the result of lower intake of feed at the reduced O2 and lower amount of internal fat. In Test 2, the largest difference was recorded in the percentage production of fish. The highest increase was achieved by rainbow trout in Var. 1 (238.8 %) and the lowest increase was achieved by brook trout in Var. 4 (122.43 %). No statistical significant differences in production and length-weight parameters were registered. The highest yield was recorded in the hybrid (88.47 %) in Var. 5.
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The effect of purging on lipid content and composition of common carp
TRYBULOVSKÝ, Filip
This bachelor's thesis deals with purging of common carp (Cyprinus carpio L.), and examines its effect on the content and composition of fatty acids and fat content. The goal of this experiment is to prove that purging has a positive effect on the carp flesh quality; that the progress and result of purging can be influenced by the input fish quality; and determining optimum time for carp purging with regard to the content and composition of fatty acids. The raising of fish was done at the ponds of the Blatenská ryba, spol. s r. o. company. The purging itself took place at the Faculty of Fisheries and Protection of Waters at Vodňany. The fish were divided into three groups according to supplementary feed. The O group was supplementary fed by cereals, the KP group by mixture of KP Len (containing rapeseed and linseed) and the PP group was left with natural diet. The fish were sampled after being placed in the purging pond. This sampling was done on the following days: 0, 14, 28, 42, 56 and 70. The fat and fatty acid analyses were performed by the Swedish University of Agricultural Sciences at Uppsala, Sweden. The KP group has demonstrably better composition of fatty acids than the O group, and its total fat content is sufficient also. The PP group also has a good composition of fatty acids, however, its total fat content is too low. The experiment has proven that purging has a positive effect on the flesh quality, if the fish are purged for a certain time period. The optimum time for carp purging, as determined by us in this experiment, is 14 - 21 days, in this period the fish have the excellent composition of omega-3 PUFA, together with a sufficient total fat content.
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