• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.6
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• pp.621-627
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• 2009

In order to standardize the juvenile abalone rearing technique, we selected sample farms by region in East, West and South coasts of Korea and Jeju island. We also have reviewed previous literature and visited farms to survey on the management of abalone juvenile production, spawning, hatching and so forth. Results of investigation are as follows: The light colors of tanks for larvae breeding are good for a frequent examination of larvae behaviour changes during the breeding period. The tank for the abalone juvenile production is a rectangular form in general and its size should amount to 3.5 m in length and 1.2 m width. It also should be built with proper drainage. The best age and size of adult for juvenile production are 3-6 years old individuals, with 9-12 cm separate burial and 125-150 g average weight. To induce spawning, the use of the exposure on air and ultraviolet ray together was the most effective. The density of larvae by plate should be 150-300 individuals and the proper stocking density was est imated and amount to 10-30 individuals. It has been shown that a correlation between water surface size($X_1$) and number of plates ($Y_1$), when producing abalone juveniles, is quite high and it is described by equation $Y_1=138.88X_1-5,736.8\;(R^2=0.9028)$. In addition, it has also been shown that a correlation between production of abalone juveniles ($Y_2$) and number of plates ($X_2$) is high and it is described by equation $Y_2=4.554X_2+12,493\;(R^2=0.8818)$. In Jindo region where a mass production of juveniles abalone has been done, it was shown, that a correlation between rearing water surface size ($X_3$) and production of juveniles abalone ($Y_3$) is very high and this relationship was described by the equation $Y_3=747.03X_2+94,359(R^2=0.9809)$. It has also been shown that a correlation between water surface size ($X_4$) and production of abalone juveniles ($Y_4$) in nationwide is high and the relationship between this variables was described by equation $Y_4=635.85X_4+99,923\;(R^2=0.9020)$.

• Journal of Aquaculture
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• v.15 no.2
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• pp.111-117
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• 2002

Effect of substrate composition, stocking density and food organisms on survival and growth of the surf clam, Spisula sachalinensis was studied. Spat collection from the substratum was the highest, when its sand size was less than 250 $\mu m4; at such substratum, survival and growth of the surf clam were also the highest. The spat (1.4 mm) grew to 4.6 mm and 8.2 mm in shell length on day 30 and 50, respectively. The relationship between shell length (SL) and shell height (SH), shell breadth (SB), total weight (TW) and shell weight (SW) of the spat are formulated by the following equations; SH : 0.7351SL+0.2272 ( $r^2$ =0.9600)i SB = 0.4037SL+0.2112 ($r^2$ = 0.9452); TW : 0.2824SL^{2.7020} ($r^2$ = 0.9820)i SW = $0.4021SL^{2.0217} ($r^2$ : 0.6169). In the substratum containing fine sand, growth and survival of the clam roared at the density of 1~2 ind./$cm^2$ were optimal. The quality of feed decreases in the following order; C. calcitrans, mixture group, I. galbana, P. lutheri, T. suecica.

• Food Science of Animal Resources
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• v.42 no.1
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• pp.128-141
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• 2022

Compared to the conventional farms (CF) rearing of broilers, the rearing management of animal welfare-certified farms (AF) must provide low stocking density, perch, air regulation, and feeding plant-based protein. This study aimed to compare the effects of rearing management in CF and AF on blood parameters, meat quality, and bioactive compound content in Ross 308 broiler chickens at the farm level before transportation to slaughterhouses. Blood and meat samples were obtained at 28-35-dayold chickens from three CF and three AF. In blood samples, low-density lipoprotein cholesterol (p<0.05), triglyceride (p<0.001), glucose (p<0.01), total protein (p<0.001), albumin (p<0.01), and white blood cell (p<0.001) levels as well as the heterophil/ lymphocyte ratio [stress index (SI), p<0.001] were lower in broilers from AF than in CF. In meat samples, shear force (p<0.001, p<0.05), and carnosine contents (p<0.001, p<0.05) in both breast and thigh meat from AF were higher than those in meat from CF. The contents of linoleic acid (p<0.001), α-linolenic acid (p<0.001), and eicosapentaenoic acid (p<0.05) were higher in the samples from AF than those from CF. This study reveals that such differences are influenced by the different rearing factors in nutrition, housing, and management practices between CF and AF. Supplementation of plant-based protein and enough space to move due to lower stocking density accounts for the large differences between them. These results can be used as preliminary data showing that the AF system reduces the SI and enhances carnosine and polyunsaturated fatty acids levels in chicken meat at the farm level before transportation.

• Korean Journal of Environmental Biology
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• v.37 no.2
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• pp.155-163
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• 2019

The Paralichthys olivaceus (mean weight 34.3±3.5 g) was used in the conduction of density experiment in this study to establish the optimal density determination for a period of 13 weeks. The density consisted of four groups. These were group 1 (500 fish, 40 fish m^-2), group 2 (750 fish, 60 fish m^-2), group 3 (1,000 fish, 80 fish m^-2) and group 4 (1,250 fish, 100 fish m^-2), each in 12.56 ㎡ circular water tanks. In the high density groups, such as groups 1 and 2, the nitrite was increased to over 21 mg L^-1 (group 3) and 25 mg L^-1 (group 4). The experiment of the groups was terminated by skin ulcers and mortality after 49 days for group 3 and 43 days for group 4. The water quality environment, such as the water temperature, dissolved oxygen, salinity and pH, remained constant. The ammonia and nitrite in groups 1 and 2 remained stable after ammonia and nitrite peak. However, the experiments in groups 3 and 4 were terminated due to the mortality induced by high nitrite. Hematological parameters, such as hemoglobin and hematocrit, were significantly decreased in the high density groups. The plasma components were significantly changed in the high density groups, such as groups 3 and 4. The mean weight of groups 1 and 2 after 13 weeks were 91.3 g and 83.7 g, respectively. The survival rates were 99.4% and 98.2%, respectively. The final FCR was 0.6 in both groups. The results of this study show that the density of 80 fish m^-2 or more induce mortality due to high nitrite with hematological changes. Additionally, they indicate that the 60 fish m^-2 indicate proper density in bio-floc environment in olive flounder weighing less than 100 g.

• Journal of fish pathology
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• v.6 no.2
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• pp.219-231
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• 1993

The author introduces the preventive and therapeutic methods of diseases in Japanese flounder which have been conducted by the Fish Disease Laboratory, the Mikamewan Fishery Cooperative Union, Ehime Prefecture, since 1982. Prevention 1. Addition of a sand substrate in the culture pond was effective to prevent ulcer disease. 2. Bathing in 0.5ppm of copper ion was effective to prevent some parasites. 3. Low stocking density of the fish reduced an incidence of edwardsiellosis or gliding bacterial disease. 4. Removal of the diseased fish prevented thd spread of lyphoeystis. 5. So-called $\pi$-water was effective to prevent the fry from some diseases. 6. Immersion of the juvenile in a sodium nifrusylate solution during transportation was effective to prevent gliding bacterial disease. Therapy 1. Sodium nifrustylate or oxytetracycline was effective to cure gliding bacterial disease. 2. Bathing in formalin(150ppm) or freshwater was effective to cure scuticociliatidosis. 3. Erythromycin was effective to cure $\beta$-hemolytic Streptococcus sp. infection. 4. Bathing in a hydrogen peroxide solution(1.5%) was effective to cure white spot disease.

• Journal of Korean Society of Forest Science
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• v.11 no.1
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• pp.25-32
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• 1970

Site-index curves for Pinus densiflora Sieb. et Zucc. grown in the middle part of Korea were developed from stem analysis data by a procedure of guide curve equation $Yt=K-ab^t$ (t=0, 1, 2, ${\cdots}{\cdots}$) and shown in Fig. 2. The stand density expressed as size-number criteria was calculated and the relation of number of tree per hectare and average DBH was presented in Fig. 3, in which soil fertility showed little effect. When this is compared to Reineke's density standards, the Pinus densiflora stand ranks high level of stocking density (Fig. 5). As a measure for estimating timber volume, the angle-summation technique revealed to result wider variation. Constructing hypothetical populations for appraising angle-summation technique, the significance of its application in silvicultural and ecological research are discussed.

• Korean Journal of Ecology and Environment
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• v.41 no.spc
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• pp.77-85
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• 2008

Grazing rates (GR) and pseudofaeces production (PFP) of native snail, Chinese mystery snail (Cipangopaludina chinensis malleata Reeve) on natural colonial morphs of Microcystis aeruginosa was measured. C. chinensis was collected from the upstream of the Geum River (Boryeong, Korea), where they co-habituated with Unio douglasiae and Lanceolaria acrorhyncha. The experiments were performed to evaluate the GR and PFP at different conditions such as; incubation time (1, 3, 5, 7, 9 and 11 hr), body size (3 to 6.1 cm, n=28), snail density (0.5, 1, 1.5 and 2.0 ind. $L^{-1}$) and prey concentration (168.3, 336.7, 505.0 and $673.0{\mu}g\;Chl-{\alpha}L^{-1}$). All experiments were triplicated, and conducted in transparent acrylic vessel (3L in volume). Regarding feeding time, a highest GR (0.538L $gAFDW^{-1}h^{-1}$) and PFP $(7.18mgAFDW^{-1})$ appeared at 1hr and 7hr after snail stocking, respectively. Interestingly, the snail, smaller than 4.5cm in body size, showed a wide range of GR ($-4.173{\sim}1.087L\;gAFDW^{-1}h^{-1}$) for the initial period (1 and 4hrs of stocking), compared to those greater than 4.5cm, which showed a stable FR, higher than 0.5L $gAFDW^{-1}h^{-1}$. Upon density effect, the density of 1.5 ind. $L^{-1}$ induced the most effective inhibition on Microcystis biomass with highest PFP. On the prey concentration, highest GR (0.897L $gAFDW^{-1}h^{-1}$) and PFP (3.67 mg $gAFDW^{-1}h^{-1}$) were induced at the level of $168.3{\mu}g\;Chl-{\alpha}L^{-1}$ and $673{\mu}g\;Chl-{\alpha}L^{-1}$, respectively. GR and PFP of this freshwater snail on the cyanobacterial bloom (M. aeruginosa) varied with the feeding conditions, and they were comparatively high for a short period of time less than 7hrs regardless of the stocking condition. Our results suggest that this freshwater snail has a potential to control cyanobacterial bloom when provided with suitable condition.

• Journal of Korean Society of Forest Science
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• v.110 no.4
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• pp.678-688
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• 2021

This study was conducted to provide growth characteristics and stand information in preparation for natural regeneration method and silvicultural treatment of seed tree method in Korean red pine stands by using the field inventoried data 18 years after the seed tree regeneration method in 2001 and analyzing the stand and sapling characteristics. The study area was located in the Research Forest of Kangwon National University, Chuncheon-si, Gangwon-do. In November 2018, we collected tree measurement factors, such as diameter at breast height (DBH), height, crown class, stem quality, tree age, and annual height increment on the established plots. We calculated the basal area, volume, height-diameter ratio (HD ratio), and additional stand density variables such as the relative density and %stocking to analyze the managed stands. The number of mother trees was 58 trees/ha, with a 17.7% stocking level, whereas the number of saplings was 2,330 trees/ha, with a 79.0% stocking level. In germination, the age distribution of saplings ranged from 2001 to 2007, with most belonging to 15-16 years. The development condition of saplings was 10 cm in DBH and 8 m in height. DBH and height were higher as the crown class is more dominant, and this difference was statistically significant in the analysis of variance and Duncan's multiple comparison test (p<0.0001). HD ratio ranged mostly between 80% and 90%, and more than 95% of sapling stems were of high quality, with a straight, unbroken top, non-sweep, and non-diseased stem. On average, the annual height increment of saplings was 21.9 cm at 1 year, 43.3 cm at 5 years, 54.3 cm at 10 years, and 64.3 cm at 15 years. The overall height growth with age increased smoothly. According to the analysis of covariance, the annual height growth by crown class differed significantly. The regression analysis parameters revealed that annual height growth increased with age and dominant crown class.

• Journal of Animal Environmental Science
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• v.18 no.3
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• pp.151-156
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• 2012

Studies of non-cage or alternative systems have been discussing in EU because the EU has banned use of conventional cages for laying hens since 2012. This survey was carried out the information related to laying hens' welfare in Korea. Laying hens' breeding systems divided into deep litter, free range and alternative system, and livestock housings divided into windowless housing and open-type housing. The ratios of trough and bell feeder types were 37.5% and 62.5%, respectively. The ratios of nipple, trough, and bucket in waterer types 75%, 12.5%, and 12.5%, respectively. What stocking density is the most appropriate for production and welfare has been aroused. All laying hen farms met the required standards of stocking density ranged from 3.4 birds/$m^2$ to 7.6 birds/$m^2$ in this survey. According to welfare standards for laying hens, perch length should not be less than 15 cm. However, most laying hen farms did not satisfied the standards. We believe that presentdata contribute to develop alternative systems and to improve animal welfare in Korea.

• Journal of Animal Environmental Science
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• v.18 no.1
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• pp.25-34
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• 2012

Noxious gases with malodorous substance concentrations in each stages of pig buildings were determined at a typical 400sow-scale farm to improve piggery environment. Using IAQ-300 and pDR-1000AN, continuous records for the concentration of $NH_3$, CO, $CO_2$, $NO_2$, $SO_2$, $H_2S$, $O_2$, and along with temperature, humidity, dust concentrates from individual pig pens were collected to analyze every 6 hours' condition of indoor environment for 24 hours' period. In most pig houses, the air quality at noon was good, while at night (00:00~06:00), air composition became noxious in all buildings. The order of buildings' air quality for 24 hrs was pregnant > farrowing > nursery > growing > finishing. The cause of air quality differences was presumed to be the differences of stocking density, defecating amount and the length of exposure time of slurry in indoors. In conclusion, well-designed building structure, proper control of stocking density, quick removal of excreta from pig pens and continuous ventilation are prerequisites to improve pig housing environment.