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Optimizing fish structure in angling ponds focusing on white fish
33-36Views:166According to new amendments of laws, commercial fishing licenses of natural waters shall not be issued from the calendar year 2016 in Hungary. However, the most settlement of white fish to angler ponds originated from natural waters. Currently, there is no sufficient quantity of fish species belonging to this group available to fulfil the settlement commitments of fish farmers. The aim of this recent study is to develop a breeding and production technology that is suitable for settlement of large quantities of this fish species of appropriate length of (4–5 cm). The following methods are investigated: aquaculture cage system (pond-in-pond system), monoculture and mixed population with different ratio of white fish in fish structure. Due to the different environmental needs of different fish species, many parameters need to be investigated, for example: stocking density, feeding, oxygen level, monoculture or mixed populations, growth potential and mortality. A preliminary experiment was carried out following the artificial propagation of ide (Leuciscus idus) following a 21-day larval rearing experiment in which the effect of different stoking density was investigated for mortality and growth. On the basis of the expected results, the optimal conditions for the aquaculture cage system will be described, regarding to the white fish stock.
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The effect of different fat content fish feed on the production parameters and meat quality of the hybrid striped bass
33-37Views:160The interspecific ’hybrid striped bass’ is the result of cross breeding. Their offspring have got good chances of growth and tolerate extreme water temperatures and the content of dissolute oxygen more than their parents. Furthermore, they are more resistant to diseases. Therefore, the hybrid is perfectly suitable for intensive fishery production.
Our experiment lasted for seven weeks. We analysed the indices of growth and production of the hybrid as the consequence of nurturing them with two feeds of high nutritive value during this period. We examined the content of fat and of fatty acids in the flesh of these fish. There were no considerable differences in terms of weight gain, feed conversion ratio and uneven growth between the two groups, while survival was less likely among the the fish which had consumed more fat. We demonstrated, examining the flesh of the individuals which had consumed feed containing lower fat content, that it was fattier and contained more dry matter than those that had been fed of higher fat content. Besides, the content of omega-3 and omega-6 fatty acids was higher in the fish that had consumed less lipids.
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Effect of different n-6/n-3 fatty acid proportion oil sources on reproduction performance and fatty acid profile of milk in modern genotype sows - Pleminary results: Preliminary results
121-128Views:127This study was conducted to investigate the effects of supplemental n-6 and n-3 fatty acids on sow’s milk fatty acid composition during the lactation period and on reproductive efficiency of sows in the subsequent gestation period. Data were collected on a total of 213 DanBred sows (108 control and 105 experimental) representing parity of 2–7, respectively. Control and experimental sows were placed in the same housing conditions during lactation and gestation period. Control group received 6.3 g of sunflower oil (SO) per kg feed as n-6 fatty acid supplementation, whilst experimental animals received the same amount of fish oil (FO) as n-3 fatty acid source. Diets were corn meal-extracted soybean meal based. The experiment was conducted in one replication as being a part of a longer and more comprehensive trial. It was found that the consumed long-chain polyunsaturated fatty acids (LC-PUFAs) appeared in the sow’s milk and changed its fatty acid profile. With this alteration, the n-6/n-3 ratio of experimental (FO) sows’ milk were narrower than in SO group (SO: 13.82 vs. FO: 5.89). The benefits of n-3 fatty acids supplementation were evident for the subsequent reproduction cycle, when experimental sows heated more reliable and earlier than control (weaning to oestrus interval: SO: 5.86 vs. FO: 4.48 days). Only 2.33% of experimental sows (FO) did not heat within 7 days after weaning, but this was 12.36% in the control group (SO). The present study requires further research to evaluate the effect of n-3 fatty acids on maintenance of pregnancy and improved subsequent litter size.
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Study of the Interaction Between Common Carp (Cyprinus carpio) and Silver Crucian Carp (Carassius auratus gibelio Bloch)
9-12Views:99Some of the main questions in the fish farming are the good manuring and the success of the feeding. For the best result is very important that only those fishes take place in the fishponds what we want. It seems to be easy but difficult to do. One of the main challenges of the successful fish production in fishponds, is to rid ponds of the silver crucian carp. In the course of the experiment, carp fry were stocked in 5 nursing ponds at the same stocking rate, with different (0-, 50-, 100-, 150-, 200%) stocking rates of silver crucian carp fry, respectively. During the rearing season, weekly test fishings were made to control the growth of the fishes. At the end of the experiment, the yield/hectar and the growth rates were calculated. The experiment proved that the presence of the silver crucian carp in the fishponds causes lower growth rates and productivity in common carp. In the control pond (without silver crucian carp), the average weight of the common carp was 25 g and the yield/hectar was over 900 kg, while in the pond with the most silver crucian carp, the average weight of the common carp was 9 g and the yield/hectar was only 158 kg.
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Study of the Interaction Between Common Carp (Cyprinus carpio L.) and Silver Crucian Carp (Carassius auratus gibelio B.)
16-19Views:81During the last few years, the spread of the silver crucian carp caused significant problems in pond fish culture. One of the main challenges of the successful fish production in fishponds, is to rid ponds of the silver crucian carp. In the course of the experiment, carp fry were stocked in 5 nursing ponds at the same stocking rate, with different (0-, 50-, 100-, 150-, 200%) stocking rates of silver crucian carp fry, respectively. During the breeding season, weekly test fishings were made to examine the growth of the fishes. At the end of the experiment, the yield/hectar and the growth rates were calculated. The experiment proved that the presence of the silver crucian carp in the fishponds causes lower productivity and growth rates in common carp. In the control pond (with no silver crucian carp), the average weight of the common carp was over 20 g and the yield/hectar was over 700 kg, while in the pond with the most silver crucian carp, the average weight of the common carp was 4.5 g and the yield/hectar was only 123 kg.