• Korean Journal of Poultry Science
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• v.30 no.2
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• pp.83-90
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• 2003

This study was conducted to determine the effects of stocking density on performance and physiological responses of egg-type breeder layers in cages. A total of 264 Hy-Line Brown egg-type breeder layers at the age of 32 weeks were divided into 4 groups with 3 replicates of 22 birds (20 females, 2 males) per replicate and assigned to four stocking density treatments with 22 birds per cage with different sizes (980, 735, 640 and 560 $\textrm{cm}^2$/bird). The birds were fed the same experimental diet ad libitum for 12 weeks, and laying performance, egg and eggshell qualities, fertility and hatchability were determined. At the end of the experimental period, 9 birds were selected in each treatment in order to measure the scores of plumage condition. Antibody titers to Newcastle disease and infectious bronchitis were also determined. No significant differences were observed in laying performances, eggshell strength, Haugh unit, fertility and hatchability among the treatments. In birds housed 640 $\textrm{cm}^2$ per bird, eggshell thickness were significantly lower (P<0.05) than those of the other groups from 7 to 12 weeks. There was no significant difference in antibody titers to Newcastle disease. In birds housed 980 $\textrm{cm}^2$ per bird, antibody titers to infectious bronchitis were significantly (P<0.05) higher than those of the other groups. With increase in the level of stocking density, the scores of plumage condition were also significantly decreased (P<0.01). This study demonstrated that moderate increment of stocking density did not resulted in reduction in laying-performances of egg-type breeder layers. However, it seemed that the higher stocking density might give more stress to the birds from physical stimuli and thus were harmful environment causing higher mortalities compared to the lower ones.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.558-569
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• 2020

This study examined the frequency of a broiler's stay in each area as stock density using an ICT-based image analysis technique from the perspective of precision livestock farming (PLF) according to the increase in the domestic broiler farms to understand the normal behavior patterns of broilers by age. The broiler was used in the experimental box (3.3×2.7 m) in a poultry house in Gyeonggi province. The stock densities were 9.5 birds/㎡ (n=85) and 19 birds/㎡ (n=170), respectively, and the frequency of stay by feeding, water, and rest area was monitored using a top-view camera. The image data of three-colored-specific broilers identified as the stock density were acquired by age (12, 16, 22, 27, and 29 days) for six hours. In the collected image data, the object tracking technique was used to record the cumulative movement path by connecting approximately 640,000 frames at 30 fps to quantify the frequency of stay in each area. In each stock density, it was significant in the order of the rest area, feeding, and water area (p<0.001). In 9.5 birds/㎡, it was at 57.9, 24.2, and 17.9 %, and 73.2, 16.8, and 10 % in 19 birds/㎡. The frequency of a broiler's stay could be evaluated in each area as the stock density using an ICT-based image analysis technique that minimizes stress. This method is expected to be used to provide basic material for developing an ICT-based management system through real-time monitoring.

• Journal of fish pathology
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• v.20 no.3
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• pp.281-289
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• 2007

We have investigated lysozyme activity and protectivity of starry flounder, Platichthys stellatus against olive flounder pathogenic bacteria, Edwardsiella tarda, Vibrio ichthyoenteri and Streptococcus iniae in varying salinities, water temperatures and stocking density. Starry flounders were susceptible to E. tarda but not V. ichthyoenteri and S. iniae. Under low salinity condition, the lysozyme activity was decreased a little compared to the control but not significant. The physiological and immune activities were normal up to 26 ℃ culture temperature and 100% stocking density; they were compromised from 29℃ and 200%, respectively.

• Journal of Aquaculture
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• v.6 no.3
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• pp.159-171
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• 1993

The effects of environmental factors (density, light, temperature) and live food on growth and survival rate of zoea and mysis of fleshy shrimp, Penaeus chinensis, were examined. The percent survival rates at the culture densities of 200 and 300 larvae per liter were significantly higher than that of 500 larvae per liter (p< 0.05). The percent survival rates at the culture densities of 100, 200, 300 and 500 larvae per liter were $90.3^{ab},\;95.2^a,\;94.3^a\;and\;86.7^b\%$ (p< 0.05). The effects of light conditions with diatom premix diet showed that continuous light was the best for the survival rate, $96.5\%$. Natural light and continuous darkness showed the survival rates $79.0\%\;and\;4.3\%$, respectively. On the rearing temperature, the survival rates were $97.3\%\;at\;19^{\circ}C\;and\;96.7\%\;at\;22^{\circ}C$ with little difference but the higher temperature resulted in faster growth. The survival rate was $51.6\%;at\;25^{\circ}C$ thus showing significant decrease compared to $19^{\circ}C\;and\;22^{\circ}C$. At this temperature the growth was also suffered. With regard to dietary value of live food, both the best survival rate and the fastest growth were obtained when 6 mixed species of diatom (A. normaii, C. simplex, N closterium, P. tricornutum, S. costatum and T. weissflogii) were provided. When single species was supplied the best survival rate $(82.1\%)$ was obtained with S. costatum, but the other species resulted in much inferior survival rates $(below\;80.0\%)$ and poor growth.

• The Korean Journal of Malacology
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• v.27 no.4
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• pp.337-343
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• 2011

In order to know the effects of rearing conditions such as water temperature, salinity, larval stocking density, kinds and amounts of food organism and seedling collection method on seedling production of the brackish water clam, Corbicula japonica, the growth and survival rate of the larvae were investigated at each rearing condition. The shell length of larvae showed faster growth at $24^{\circ}C$ and $27^{\circ}C$, and survival rate showed good results at $18^{\circ}C$ and $21^{\circ}C$. Based on growth and survival rate according to water temperature, the optimal water temperature for larvae rearing was $24^{\circ}C$. At the salinity of more than 3 psu, the growth and survival rate were higher than 0 psu. The optimal salinities for larvae were 6-9 psu. Growth and survival rate of larvae were high at low stocking density and the optimum stocking density of larvae was 10 inds./ml. Daily feeding concentrations of 10,000-20,000 cell/ml of food organisms mixed Pavolva lutheri, Isochrysis galbana and Chaetoceros calcitrans were very effective. Full grown larvae collection from various substratum was significantly higt in sand, especially sand size was less than 0.25 mm.

• Journal of Aquaculture
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• v.11 no.4
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• pp.565-572
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• 1998

Survival rate of larval red spotted grouper, Epinephelus akaara is very low, because mouth size of the larvae is too small to eat normal sizes of rotifers. In order to enhance larval survival, optimal culture conditions for larvae using different live foods and water temperatures were studied. Bigger live food produced larger size of rotifer, when the rotifer was cultured with three different live foods such as Tetraselmis tetrathele, marine Chlorella and Nannochloris oculata. Also, the size of rotifer produced was temperature-dependent showing that higher water temperature induced smaller rotifer. Survial rate of the larvae increased with the increase of water temperature up to $29{\circ}C$. Also, higher larval survials were found at the food density of 15 to 20 individuals per milliliter. The larvae fed L-type or small individuals of L-type rotifer died all within a week, although the larvae fed S-type or small individuals of S-type one survived successfully during this period. The size of small individuals of S-type rotifer collected through fine net became larger in a few hours within larval culture tank. Survival rate of grouper larvae with initial stocking density of 40 thousands in 6-ton concrete tank was 6.3% in 10 days and 0.2% in 53 days after hatching, respectively. Total length of the larvae reached around 29.5 mm in 53days after hatching.

• Korean journal of applied entomology
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• v.58 no.1
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• pp.69-76
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• 2019

This study was evaluated to increase the production efficiency of Gryllus bimaculatus De Geer, which are recently increasing attention as industrial insects in Korea. In this study, the hatching rate and larval period were investigated along with temperature and humidity, as well as the survival rate and ovipositional temperatures along with rearing density. The optimum relative humidity for hatching was highest at 90%, which shows the hatching rate of 90%. The highest hatching rate was 98.3% at $20^{\circ}C$. The hatching period was shortest at $35^{\circ}C$ incubation, which shows 7.1 days in average. The survival rate at 3,000-20,000 individuals in the breeding container was 34-18% after rearing for 35 days. In the effect test of feeding vegetables, the survival rate was 1.8 times and the biomass weight 2.5 times higher than that of normal individuals respectively. The number of laying eggs by temperature was highest at $25^{\circ}C$, which shows 1,710 eggs after reading for 30 days.

• Journal of the Korea Organic Resources Recycling Association
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• v.13 no.2
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• pp.98-106
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• 2005

Population dynamics in the vermicomposting bed was investigated. And harvesting efficiencies of earthworm attracting traps with different attractants, mesh sizes of net and covering materials was evaluated. Peak density of earthworm population was $5kg/m^2$ and therafter its desity kept $4.4{\sim}5.0kg/m^2$. It was evaluated that suitable mesh size of the net was 7mm and proper covering materials of the earthworm attracting trap was cotton quilt. The earthworm harvesting efficiency of trap with attractant was much higher than that of trap without attractant. With more amount of attractant in the trap and with longer setting period of trap onto the vermicomposting bed, the earthworm attracting trap harvested more earthworms. Crushed pear-peel attracted much more earthworms than paper mill sludge, but it was difficult to supply enough amount of crushed pear-peel for practical need. Sugar solution(10%) with tab water was proven to be an alternative to crushed pear-peel because its attracting effect on earthworm was as high as crushed pear-peel and it was easy to prepare and supply in large quantity.

• Journal of the Korea Organic Resources Recycling Association
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• v.1 no.2
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• pp.259-266
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• 1993

This experiment was carried out to the effect of population densities on the growth reproduction, cast production of the earthworm and chemical composition of worm casts. The population densities of 50, 100, 150, 200 and 250 individuals of the earthworm fed with cow manure was studied in rearing box($6,400cm^3$) and fertility stage during a period of 60 days. The results were summarized as follows 1. Survival rates(SR) of the earthworms had significantly positive correlated with increasing rate(IR). But, survival rates(SR) and increasing rate(IR) had significantly negative correlated with reproductive efficiency(RE). 2. The ranges of optimum population densities estimated were $42.7cm^3-128.0cm^3/worm$. 3. The cast production estimated were 36.5mg-80.9mg/day/worm grown in optimum population densities(50-150 worms/$6,400cm^3$). 4. The earthworm castings are an excellent soil conditioning material with a high chemical composition and their physical properties.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.281-282
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• 2001

본 연구는 현재까지 국내에서 가숭어, Chelon lauvergnii의 성숙 및 인공 종묘 생산에 관한 구체적인 연구 보고는 매우 미흡한 실정임을 고려, 가숭어의 효과적인 인공 종묘 생산을 위한 기초 자료로서 산란기 특성 조사 및 부화 자어에 대한 rotifer, Artefnia, 배합사료 공급에 따른 성장과 생존을 조사하였다. 또한 rotifer와 brine shrimp, Artemia nauplius를 오징어 간유, 식물성 플랑크톤 건조 분말인 Maxima$^{TR}$ , Chlorella sp.로 각각 영양 강화한 후 치어에 공급시 자어의 성장과 생존에 대한 그 효과를 비교 분석하였다. 아울러 밀도별 사육 실험을 통한 적정 밀도를 규명하여 가숭어 종묘 생산시 효율적이고 경제적인 기술을 개발하고자 본 연구를 수행하였다. (중략)