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The effects of bioactive feed additives for the production parameters of common carp (Cyprinus carpio) fingerlings in intensive recirculating system
Published March 24, 2015

For the appropriate quantity and quality of fish meat the pond farmers need to use up to date nutrition and feeding technologies. Recently the intensification of the carp production is stepping up with the availability the proper quality of the artificial feeds. The using of different feed additives make a better feed conservation ratio, faster... growing rates and more uniform stocks.

In our experiment what is made with common carp (duration of the experiment was 8 weeks long) we compared two different kinds of feed additives in different doses. One of them contains only natural mineral elements and the other additive is a natural origin probiotics. Both additives were used in the quantity of 0.5, 1 and 2% of the total feed. By the result of the 8 weeks experiment it could be said, that the using of the humic acid based mineral elements feed additive. Makes a better FCR comparing with the control stock, but was not as good as the using of the probiotics. At the humic acid treatments the more doses, the better FCR value, but at the probiotics it wasn’t true. The 0.5% probiotic treatment gave the best result. It is concluded that the using of the probiotic feed additives always gave a better performance of the fishes (average weight, biomass, FCR) than the humic acid treatments. The using of the feed additives hasn’t got an influence for the survival rate of the carps.

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The effects of the nanoselenium supplementation to the production parameters and the selenium retention of the red drum (Sciaenops ocellatus)
Published March 20, 2014

The selenium is an essential trace element with antioxidant effect, constituent of many enzymes, natural component of the body of the animals. The addition to the fish feed as micro element supplementation is generally accepted. Numerous animal experiments veryfied, that the antioxidant effect of the nanoselenium is higher than other selenium f...orms. But no much information is available of the usuage at fish.

In the experiment were investigated the effects of the nanoselenium supplementation of a commercial fish feed were investigated to the production parameters and the body tissue composition. The correlation between the accumulated selenium content of the body and the treatment, and the feed conversation was also statistically analyzed beside the production parameters. Furthermore we were curious, if can be toxic the nanoselenium in higher doses.

The experimental stock was placed into 12 plastic tanks (each 70 l water vol.) in a recirculation system for larval rearing. The salinity and the water temperature was constant during the 8 week long experiment. The feeding was ad libitum, 4 times a day. Beside the control five (1, 1.5, 2.5, 5.5, 10.5 mg Se kg-1) duplicated treatment were set.

According to the results, from the production parameters only at the value of FCR and the survival was found significant difference (p<0.05) between the groups. However strong correlation (r=0.752–0.780, p<0.01) was determined between the treatment and the accumulated selenium levels. To analyzed the free fatty acid contentof the fish, we realized, that the selenium uptake significanly enhanced this level at all treatments. The greatest change was found in case of the type n-3 fatty acids.

Established by the results, the higher intake than 0.5 mg Se kg-1 was not changed significantly the production parameters, nevertheless to increase the selenium content of commercial feeds to 1.5 mg Se kg-1 could be rewarding on the rearing of red drum.

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The use of essential trace elements in the juvenile rearing of barramundi (Lates calcarifer
Published March 20, 2014

Barramundi (Lates calcarifer L.) is a predatory fish species native in Southeast Asia and Australia. Based on the geothermal potentiality of Hungary the warm-water fish can be reared successfully. Zooplankton in the wild contains minerals in a higher concentration than the usually fed newly hatched Artemia nauplii, therefore essential trace ele...ments, such as cobalt, zinc and manganese play an important role in the larviculture of barramundi. Cobalt is vital in trace amount for many living functions of vertebrates, however, lower number of papers are available considering the nutritional aspects. Nevertheless. improved growth performance was observed in cases of some fish species when diet was supplemented with CoCl2. Zinc and manganese are also vital for optimal growth and accordingly are investigated and applied diet supplements in aquaculture.

The main aim of the recent study is to investigate the effects of cobalt, manganese and zinc on the growth performance and homogeneity of fish when a commercially available dry diet is supplemented with trace elements individually and in combined treatments. A total of 6 treatments were set in a randomized blocked design where the concentrations of the applied elements were 50 mg kg-1 for CoCl2, for ZnSO4 and for MnCl2 individually, as well as for CoCl2 along with ZnSO4 and for CoCl2 along with MnCl2 in combination. Although the production parameters of larval barramundi were positively affected by the addition of trace elements when the retention of minerals occurred through nourishment living organisms, statistically no differences were found between the treatments considering the growth performance of barramundi juveniles either when dry feed was supplemented with cobalt, manganese or zinc (p>0.05). While the use of cobalt and manganese in combined treatments produced a less uniform larvae in size and as a consequence of increased heterogeneity, survival was significantly reduced by the cannibalism, the sizes distribution of barramundi juveniles wasn’t affected by the dry diet supplementation of these elements.

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Practical experiences of a designing and operating a pilot aquaponic system
Published March 20, 2014

Aquaponics is the combination of fish farming (aquaculture) and the soilless cultivation of plants (hydroponics). The aquaponics system is an artificial, recirculating ecosystem, in which bacterial processes convert the waste materials in the water used for fish rearing into plant nutrients, and therefore with the generated heat it is suitable ...for culturing economically valuable plants, and thus it mitigates the nutrient laden and quantity of the intensive fish producing systems’ effluent water.

The primary goal of our 12 separate unit’s aquaponics system was to gain experience. We would like to find the right plant species, which are fit for that medium, and their crop can be sold. Besides the plants, our attention focused on the fish. Two fish species were included in the experiments, the common carp and barramundi. It was difficult to create them a perfect living space, besides a constantly changing conditions temperature. Apart the above mentioned we had a problem with the number of individuals per tank, the deformity of the fish body and the too high volume of pH (we registered continuous values above 8.4). We get by carps 4.7 grams of weight gain during 15 weeks, because of the bad conditions.

The main problems at the plants are caused by aphesis and protection against sunburn. Even so we have got the multiples of field yields for each plant species. At salad has grown twice of field yields, tomatoes one and half, kohlrabi than 3.5 times more. The causes of multiple yields are the continuous balanced water and the nutrient uptake of plants. Each plant species fit for cultivating in aquaponics and their crops are delicious, chemical -free, safe and marketable. The plants should be more concentrated. After the experiment, it has been determinated that the carp is suitable for aquaponics, but greater weight gain could be achieved with optimal selection of size of rearing units.

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The effect of different fat content fish feed on the production parameters and meat quality of the hybrid striped bass
Published February 10, 2013

...5); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">The 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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