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The use of essential trace elements in the juvenile rearing of barramundi (Lates calcarifer
33-38Views:158Barramundi (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 elements, 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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Examination of the population density and sowing date of different maize genotypes in the Hajdúság region
111-115Views:115The experiment was carried out 6 km from Debrecen, next to the main road 47 on a homogeneous field on brown forest soil. Five corn hybrids were tested in the trial (DKC 4795, DKC 4995, KWS Kornelius, NK Cobalt, PR37 N01) at three different sowing times (early – 5th April, average – 21st April, late – 10th May). At each sowing time, three different plant densities were applied (modest – 58 500 plants ha-1, average –70 200 plants ha-1, high – 82 300 plants ha-1). The agrotechnics applied
in the experiment satisfied the requirements of modern corn cultivation.In the study, the best yield result was achieved with the early sowing time out of the three examined sowing times (11 315 kg ha-1), which was significantly different (LSD5%=495 kg) from that of the average sowing time (10 690 kg ha-1), however, there was no statistically justifiable difference between the yield results of the early and the late sowing times. There was a significant difference also between the average and late sowing time. Our results indicate that the different sowing times resulted in a different flowering times. Consequently, the stands of early and late sowing time reached this critical stadium of growth under proper climatic circumstances (precipitation: 39 mm and 136 mm, average temperature at flowering: 18.1 oC and 20.3 oC), while flowering in the case of the average sowing time of 21st April was in the first half of July and the average temperature at flowering was warmer (23.2 oC) with only 10 mm precipitation.
In the experiment, the plant density response was also examined. According to the measured data, four of the five hybrids responded badly to the increasing plant density. We found that the plant density of 58 500 plant ha-1 gave the largest yield results (DKC 4995 11 794 kg ha-1 – NK Cobalt 10 998 kg ha-1, average of five hybrids: 11 430 kg ha-1), while the lowest yields were obtained at the plant density of 82 300 plant ha-1 (KWS Kornelius 11 037 kg ha-1 – NK Cobalt 10 019 kg ha-1, average of five hybrids 10 720 kg ha-1). The difference between the two plant densities was significant (LSD5%=494 kg), however, the 70 200 plant ha-1 plant density did not show any statistical difference from neither the 58 500 ha-1 nor from the 82 300 plant ha-1 stands. When examining the data of the hybrids separately, we found that there was a significant difference between the average yield of the lowest and highest plant densities only in the case of three (DKC 4795, DKC 4995, NK
Cobalt) out of the five hybrids (DKC 4795: 11 757 kg ha-1 – 10 857 ha-1 where LSD5% =816 kg; DKC 4995: 11 794 kg ha-1 – 10 738 kg ha-1 where LSD5%=853kg; NK Cobalt: 10 998 kg ha-1 – 10 019 kg ha-1 where LSD5%=630 kg ha-1), while a significant difference between the second and third plant densities was observed only in one case (DKC 4995: 11 726 kg ha-1 – 10 738 ha-1 where LSD5%=853 kg). In all other cases, there was no statistical difference between the different
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Use of essential trace elements enriched Artemia in the larval rearing of barramundi (Lates calcarifer)
11-16Views:135Artemia is a vital nutriment in the rearing of barramundi (Lates carcarifer), however it’s mineral trace element content does not cover the requirements of the larvae. In our experiment the assumption was wether the cobalt, zinc and manganese concentration of Artemia could be increased during a 24 hours of enrichment period, as well as we wanted to investigate the resulted interactions between the elements. For this purpose 50, 100 and 1000 mg l-1 cobalt-chloride treatements (Co50, Co100, Co1000) were applied while in the case of 50 and 100 mg l-1 treatments the enrichment was also complemented with zink-sulphate and manganese-chloride in the same concentrations. According to the results the zooplankton were able to accumulate cobalt in higher amount, and yet zinc and manganese had no significant effect on each other, a strong synergistic effect occurred between cobalt and manganese. After the enrichment period the impact of essential trace element supplemented live feed on the survival and growth of barramundi larvae was also studied. The experiment was carried out by using 15 days-old larvae applying a total of 9 treatments for two weeks (Control, Co50, Co100, Mn50, Mn100, CoZn50, CoZn100, CoMn50, CoMn100), in duplicates. Considering the per cent of survivals, no significant difference was observed between the treatements (P>0.05). In the case of CoMn50 and CoMn100, the loss statistically increased (P<0.05) compared to the Control (80.5±4.95%) group. Our results show, that the Mn100 and CoMn100 treatements resulted in ignificantly higher (P<0.05 ) in divid ual bod y w eight s, how ever taki ng the survival also into consideration the Mn100 treatements proved to be the most
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The impact of various grape stock cultivars on the As, Cu, Co and Zn content of the grape berry (must, seed)
39-44Views:133Scientific research from the last decades showed that the inappropriate industrial and agricultural production caused an abnormal increase of the potentially toxic elements in the soil. Unfortunately the acidification of the soil is an increasing problem in Hungary. According to Várallyay et al. (2008) 13% of the Hungarian soils are highly acid. Accumulation of toxic elements differs in the genetically diverse plant species. The root of the plant constitutes a filter so that the rootstock is also kind of a filter system, which may prevent that the scion part (such as berry) accumulate high levels of various potentially toxic elements from the soil. The aim of research was to determine how different grape rootstocks influence the As, Co, Cu and Zn content of the musts and seeds. Thus, specifying which of the grape rootstocks takes up the lowest level of these 4 elements (As, Co, Cu and Zn), and accumulates in berries, so could reduce the potentially toxic element load of the grape berries. The grape rootstock collection of the University of Debrecen was set up in 2003 in 3x1 m spacing on immune sandy soil. Grafting of ‘Cserszegi fűszeres’ was started in 2010. We could evaluate yields harvested from 12 rootstock varieties of the experiment in October 2011. We obtained valuable differences in the arsenic, copper, cobalt and zinc concentrations of musts and seeds of ‘Cserszegi fűszeres’ grafted into different rootstocks. The results obtained from the 2011 harvest support the statement that the choice of rootstock might be an important factor to increase food safety. The differences in concentration of the four elements observed in case of the rootstock may have been caused on one hand by the rootstock effect, and on the other hand, the vintage effect has a very significant impact on the vines element uptake. Several years of experimental results will be needed to answer these questions.
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The effect of cobalt-chloride on the production parameters and homogenity of barramundi (Lates calcarifer) larvae
21-25Views:143Barramundi (Lates calcarifer) is a predatory fish species native in Southeast Asia and Australia. Based on the geothermal potentiality of Hungary the high market potential warm-water fish barramundi can be produced economically. Living nourishment organisms such as Artemia nauplii play an essential role in the larval rearing of barrramundi. However, zooplanktons in natural aquatic enviroments contain minerals in a higher concentration than the usually fed newly hatched Artemia. Therefore the goal of recent study was to investigate the effect of cobaltchloride on the larval growth and survival of barramundi when fed individually and combined with Zn and Mn supplemented Artemia.
In our experiment a 24 hours period was used for the enrichment of newly hatched Artemia nauplii with cobalt chloride in itself, as well as in combination with zinc sulphate and manganese chloride. A total of 1900 barramundi larvae from 15–30 day post hatching were fed with supplemented Artemia in 9 groups of treatments in duplicate. The growth performance and elemental concentration of 40 larvae from each group was determined. All the groups produced significantly improved growth compared to the control (p<0.05). The lower concentration of individual Co supplementation resulted in a higher growth performance while the opposite dose relation occured when combined the Co with Mn. Cobalt had a significant negative effect on the Mn uptake of the larvae – significantly higher Mn accumulation compared to the control group was only observed when Mn was fed in itself (p<0.05). In case of Co-Zn-1 and Co-Zn-2 treatments significantly higher Zn concentration was measured than in the others (p<0.05).