• 한국수산과학회지
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• 제42권4호
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• pp.349-353
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• 2009

Two feeding trials were conducted to evaluate the soybean meal as a substitute for the fish meal in diet (experiment I), and experimental practical diet and commercial diet (experiment II) for growth of far eastern catfish. In the experiment I, three replicate groups of juveniles (average weight 7.2 g) were fed one of diets containing 0, 10 and 20% soybean meals for 66 days. Survival and final mean weight were not significantly affected by dietary soybean meal levels. No significant differences were observed in feed efficiency, protein efficiency ratio and protein retention of fish fed between 0% (control diet) and 20% soybean meal diets. However, fish fed 10% soybean meal diet showed the lower feed efficiency, protein efficiency ratio and protein retention, and higher daily feed intake compared with fish fed control diet and 20% soybean meal diet. The contents of moisture, crude protein, crude lipid and ash in the whole body were not significantly affected by dietary soybean meal levels. In the experiment II, three replicate groups of juveniles (average weight 7.3 g) were fed either the formulated diet or commercial diet for 66 days. Survival and final mean weight were not significantly different among treatment. Significantly higher feed efficiency, protein efficiency ratio and protein retention, and lower daily feed intake were observed in fish fed experimental practical diet compared with fish fed commercial diet (P<0.05). Proximate compositions of the whole body were not significantly affected by diets. The results of these studies suggest that soybean meal can be used as a substitute for fish meal up to 20% in diet, and the dietary formulation used in the experiment II could be applied to the practical feed for far eastern catfish.

• Fisheries and Aquatic Sciences
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• 제17권4호
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• pp.455-459
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• 2014

A feeding trial was conducted to determine the optimum dietary protein requirement of young far eastern catfish Silurus asotus. Five isocaloric diets were formulated to contain graded levels of protein (35, 40, 45, 50, and 55%). Triplicate groups of fish (initial body weight of 44 g) were hand-fed to apparent satiation for 9-weeks. Weight gain and specific growth rate of fish fed 55% protein diet were significantly higher than those of fish fed 35 and 40% protein diets, but not significantly different from those of fish fed 45 and 50% protein diets. The feed efficiency of fish fed 50 and 55% protein diets was significantly higher than that of fish fed 35, 40 and 45% protein diets. The protein efficiency ratio of fish fed 40% protein diet was significantly higher than that of fish fed 45, 50 and 55% protein diets, but not significantly different from that of fish fed 35% protein diet. The dietary protein level significantly affected whole body lipid and moisture contents. The results of this study suggest that the 45% protein in the diet is optimal for maximum growth of young far eastern catfish weighing in the range of 44 to 227 g.

• 한국수산과학회지
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• 제46권3호
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• pp.310-314
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• 2013

This study investigated the utilization of beef tallow and dextrin as non-protein energy sources in the diet of juvenile far eastern catfish Silurus asotus. Three replicated groups of juveniles (initial mean weight of 3.6 g) were fed diets containing high levels of beef tallow or dextrin for six weeks. The final mean weight of fish fed on a 17% lipid diet with a high level of beef tallow was significantly higher than that of fish fed on a 9% lipid diet with a high level of dextrin (P=0.04). No significant differences were observed in the feed efficiency and protein efficiency ratio of fish fed on the experimental diets. Crude lipid content and the C18:0, C18:1n-9 and C18:2n-6 contents of whole-body fish were significantly affected by diet (P<0.05). The results of this study suggest that beef tallow is better than dextrin as a non-protein energy source for improving the growth of juvenile far eastern catfish, and that beef tallow could be economically used as an ingredient in practical feed.

• 한국수산과학회지
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• 제55권5호
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• pp.541-548
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• 2022

Biofloc technology (BFT) systems provides an additional protein source for fish by converting waste in microbial flocs. Therefore, we aimed to determine the difference in the protein levels of the diet of Far Eastern catfish Silurus asotus reared in BFT and FW systems. We applied a two-way (six protein levels × two aquaculture systems) ANOVA design. We formulated six experimental diets to contain different protein levels (CPs)- 20%, 25%, 30%, 35%, 40% and 45%-referred to as the CP20, CP25, CP30, CP35, CP40 and CP45 diets, respectively. We randomly distributed 900 fish into 36 (18 each for BFT and FW), 300 L tanks (25 fish/tank) with three replications of each diet for 4 weeks. The weight gain (WG) and specific growth rate (SGR) considerably improved as the dietary protein level increased in the formulated diets. The BFT fish showed higher growth performance with any experimental diet than the FW fish. The growth performance of the fish fed the BFT-CP35 diet was higher than that of the fish fed the FW-CP45 diet. In conclusion, the cultivation of Far Eastern catfish (S. asotus) in BFTs can be carried out under reduced dietary protein levels.

• Fisheries and Aquatic Sciences
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• 제14권4호
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• pp.417-420
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• 2011

In this experiment, we examined the survival, fertilization, hatching times, and hatching rates of Far Eastern catfish Silurus asotus at pH ranging from 2 to 13 under laboratory conditions. Eggs could be fertilized at pH 3-12. In a hatching experiment, mortality was first observed at pH 13, when all fertilized eggs died within 8 min, followed by pH 2 (30 min), pH 12 (60 min), pH 3 (4 h), and pH 11 (5 h). Hatching only occurred at pH 4-10, with the highest hatching rate at pH 7 (52%) and the lowest at pH 10 (24%). Hatching rates in acid solutions were higher than in alkaline solutions, although the difference was not significant. Hatching was first observed at pH 10, beginning 27 h after fertilization and ending at the 31 h. A clear difference was observed between hatching times, ranging from 31 to 64 h and increasing in order with descending pH.

• 한국발생생물학회지:발생과생식
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• 제22권2호
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• pp.165-174
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• 2018

The aim of study is to contribute to this knowledge-base by investigating the respiratory function, the metabolic rate and the difference of physiological responses un-der low water temperature ($20^{\circ}C{\rightarrow}15^{\circ}C$) stress be-tween diploid and triploid far eastern catfish, Silurus asotus. During the 48 hrs of water temperature stress exposure time, the respiratory frequencies, $CO_2$ and ${NH_4}^+$ concentrations of diploid had higher values than those of triploid (p<0.05). However, pH of triploid was higher than those of diploid (p<0.05), and oxygen consumption rate was not different between diploid and triploid (p>0.05). The level of plasma cortisol and plasma glucose of triploid was lower than those of the diploid (p<0.05). However, in case of lactic acid, there were not significant between triploid and diploid (p>0.05). These results suggest that diploid was more sensitive for low water temperature stress response than triploid in this species.

• 한국어병학회지
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• 제32권1호
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• pp.21-28
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• 2019

It has been reported that various anti-oxidant substances stimulate non-specific immune responses in fishes. In this study it was examined whether N-acetylcysteine (NAC), a precusor for anti-oxidant glutathione (GSH) synthesis, can modulate non-specific immune function in Far Eastern catfish Silurus asotus. Immune functions were assessed using the respiratory burst activity monitored by chemiluminescence (CL) responses in isolated leucocyte. NAC stimulated CL responses with doses of 10 or 100 mg/kg, but not with 1 mg/kg after 48 hr injection. It was observed with 10 mg/kg NAC that CL activity continued to elevate from 24 hr through 96 hr post-dosing, and returned to the near preinjection level by 10 days. To understand whether NAC can also activate CL activity in vitro, NAC was directly added to isolated catfish leucocytes. It was observed, however, that NAC can not stimulate CL at reasonable concentration ranges in vitro. As NAC is a precursor for the strong anti-oxidant glutathione (GSH), a putative immune stimulator, it was assessed whether GSH can also stimulate CL responses. Observed results show that GSH activated CL both in vivo and in vitro. The data obtained collectively support the proposition that NAC indirectly stimulates non-specific immune functions in catfish by enhancing GSH biosynthesis, but not by direct action of NAC. Such effects may have beneficial significance in aquaculture for practical utilization.

• 환경생물
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• 제39권1호
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• pp.55-67
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• 2021

메기(Silurus asotus)를 대상으로 210일간 기아 시 계측형질 및 체 절단면 형질을 측정하여 그 기아 효과를 조사하였다. 실험 종료시 섭이군의 생존율은 92.2±0.47%였으며, 기아군에서는 74.4±2.59%의 생존율을 보였다. Ls, DALPO/Ls, DADOP/Ls, ED/Ls, CH/Ls, BDAA/Ls, BDMA/Ls 및 BWAA/Ls의 8개 항목에서 유의한 차이를 보였으며(p<0.05), 다른 16개 항목 DALAD/Ls, DPDPL/Ls, HPLAA/Ls, HALAV/Ls, HALOP/Ls, DAUPO/Ls, DADAV/Ls, DADAA/Ls, Max BL/Ls, Man BL/Ls, LD/Ls, HWOP/Ls, DAUF/HL, DAUS/HL, IW/HL 및 DAUE/HL에서는 초기군, 섭이군 및 기아군의 세 그룹 간 유의한 차이가 없었다(p>0.05). 섭이군은 각 체 절단면에서 기아군보다 더 높은 전체 높이(THX), 더 넓은 너비(WX) 및 더 넓은 면적(AX)을 보였다. 본 연구는 메기의 기아 상태에 대한 외형 및 체 절단면 형질에 대한 정보를 제공한다. 이는 메기에 대한 먹이 조절에 대한 방법을 보조하고 영양상태를 나타내는 기본 기초자료로 활용될 수 있을 것이다. 또한, 본 연구에서 사용한 조사 분석 방법을 타 어종에서 적용 시 그 영양 상태에 대한 정보를 파악하는 데 유용하게 활용될 수 있을 것으로 사료된다.

• 한국양식학회지
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• 제13권4호
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• pp.359-362
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• 2000

Mitotic gynogenesis was induced in the far eastern catfish, Silurus asotus using UV-irradiated heterospecific sperm and cold shock treatment. Eggs were activated with the sperm of mud loach, Misgurnus mizolepis which has been irradiated with UV at dose of 9,000 ergs/$mm^2$. To determine the optimum duration required to prevent the first cleavage, a cold shock at 4$^{\circ}C$ with duration of 20, 30 or 40 min was applied to the eggs 50 min after activation. To induce diploidization of mitogenesis, the most effective protocol was to apply cold shock to 50-min old (after activation) eggs at 4$^{\Circ}C$ for 30min.

• 한국양식학회지
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• 제15권4호
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• pp.275-277
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• 2002

양식 산업성이 큰 메기 S. asotus를 대상으로 한 염색체 공학의 기초 자료를 얻기 위하여 본 연구를 수행하였다. 본 종의 난발생 중 핵분열(karyokinesis)을 조직학적으로 조사한 결과, 수온 24${\pm}$0.5$^{\circ}C$ 조건에서 핵분열은 수정 후 31분에 가장 현저하였으며, 이 시기는 메기에서의 제 1 난할 중기에 해당하였다.