• Korean Journal of Ecology and Environment
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• v.37 no.3 s.108
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• pp.319-331
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• 2004

This study was conducted to evaluate the ecological impact of freshwater bivalve (Corbiculidae) on plankton communities in experimental enclosure systems (2 m ${\times}$ 2 m ${\times}$ 2 m). During the acclamation period of one month, cyanobacteria, including Microcystis viridis and Microcystis aeruginosa, dominated in both control and treatment enclosures with no noticeable density difference. After the addition of 100 mussels, dominant species of phytoplankton shifted from Microcystis to Scenedesmus in concert with slight decrease in the cell density and the increase of N/P ratio. However, cell density in the control quickly increased, accompanied with changes of dominant species to Oscillatoria spp. With the introduction of additional 500 musseles in the treatment enclosure, dominant phytoplankton species in both enclosures were replaced with Selenastrum spp. and Cryptomonas sp. In the initial stage, the total zooplankton abundance in the control was higher than that of treatment, but it was reversed after the addition 100 mussels. After mussel density increased up to 600 indivisuals, zooplankton density in the treatment decreased with dominance of small taxa, such as rotifers and nauplius. However, abundance and carbon biomass of large zooplankton, such as Bosmina longirostris and Diacyclops thomasi were maintained in a high level compared with those of control. During the study period, Chl. a concentration in mussel treatment and control increased with DIP and $NH_3-N$, respectively. Due to the increase of $NH_3-N$, especially after the introduction of additional 500 mussels, nitrogen limitation did not occur in the treatment enclosure in contrast with strong nutrient limitation occurred in the control. These results indicate that filter-feeding Corbicula could exert important impact on nutrient recycling and plankton community structure in a freshwater ecosystem, through direct feeding and competition for the same food resource as zooplankton on one hand, and through alteration of nutrient availability on the other.

• Korean Journal of Ecology and Environment
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• v.36 no.2 s.103
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• pp.181-190
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• 2003

An investigation was conducted on the aquatic environment of the Okchon Stream watershed six times from May to September 2002. The results of investigation revealed that variation of environmental factors were quite significant for each stream and reach, showing a significant difference between running water and stagnant water. Aquatic nutrients were relatively low in the upstream, gradually increasing as the influx of treated wastewater into the stream increased. This suggests that the point source definitely affected the nutrient content of the stream. In particular, the variations of SRP and $NH_4$ were very distinct in the watershed compared to other nutrients. Thus, it can be considered as a major factor in evaluating the effect of treated wastewater. Immediately after the influx of treated waste-water, the average content of SRP rose to 919.3 ${\mu}g$ P/l. This was a very effective level in the watershed, suggesting that the percentage of the nutrients in the water was controlled by the content of P. The constant supply of treated wastewater was found to be a critical factor in triggering the increase in chl-a in the embayment of the stream. With the proliferation of the blue-green algae, the content of chl- a ranged 234.5${\sim}$1,692.2 ${\mu}g/l$. The maximum standing crops exceeded $1.0{\times}10^6$ cells/ml in August, which was more than 200 times the level for red tide in the freshwater. This result was well reflected in other environmental factors, with 100% of AFDM/TSS reflecting the severity of water pollution by algae. Therefore, the reduction of P and N con-tents in the treated wastewater is critical in improving the aquatic environment of the stream as well as water quality management for the reservoir.

• Korean Journal of Ecology and Environment
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• v.48 no.2
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• pp.108-114
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• 2015

Single - and combined effects of a domestic freshwater bivalve Unio douglasiae (7.6~8.6 cm in shell length) and zooplankton Daphnia magna (1~2 mm in body size) were examined to understand whether they inhibit the growth of harmful cyanobacterial bloom (i.e. Microcystis aeruginosa) in a eutrophic lake. The experiments were triplicated with twelve glass aquaria (40 L in volume); three aquaria without mussel and zooplankton, served as a control, three zooplankton aquaria (Z, density=40 indiv. $L^{-1}$), three mussel aquaria (M, density=0.5 indiv. $L^{-1}$), and three mussel plus zooplankton aquarium (ZM, density=40 indiv.Z $L^{-1}$ plus 0.5 indiv.M/L), respectively. Algal growth inhibition (%) calculated as a difference in the concentration of chlorophyll-a (Chl-a) before and after treatment. Chl-a in all aquaria decreased with the time, while a greatest algal inhibition was seen in the ZM aquaria. After 24 hrs of incubation, Chl-a concentration at the mid-depth (ca. 15 cm) in ZM aquaria reduced by 90.8% of the control, while 63.2% and 79.8% in Z and M aquaria, respectively. Interestingly, during the same period, the surface Chl-a was diminished by 51.9% and 65.4% relative to the control in Z and ZM aquaria, while 27.4% of initial concentration decreased in M aquarium, respectively. These results suggest that 1) this domestic freshwater filter-feeding bivalve plays a significant role in the control of cyanobacterial bloom (M. aeruginosa), and 2) the combination with zooplankton and mussel has a synergistic effect to diminish them, compared to the single treatment of zooplankton and mussel.

• Journal of Animal Environmental Science
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• v.2 no.1
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• pp.41-52
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• 1996

This experiment was carried out to study the effect of sprinkler and fan cooling system on the physiological parameter, milk production and milk composition for Holstein cows in hot, humid climates. Thirty cows were assigned to one of two sections of open-sided loose barn. Water nozzles of sprinkler system were spaced in line at 1.2m intervals. Forced air was provided by 85cm diameter fans at rate of 3.4㎥/sec. The results obtained from these experiments are as follows: 1. There was no significant difference in meteorological data between control and fan + sprinkler cooling system(treatment group). 2. Skin temperature and rectal temperature of the treatment group were significantly lower than those of the control group (32.96 : 39.53$^{\circ}C$ vs 34.02 : 41.21$^{\circ}C$ respectively) (P<0.05). 3. Serum cortisol concentration of the treatment group(0.90$\mu\textrm{g}$/dL) was lower than that of control group(1.44$\mu\textrm{g}$/dL)(P<0.05). 4. Milk production of cows cooled with a sprinkler and fan cooling system was significantly higher than that of no cooling system (P<0.0l). 5. Lactose, protein and solid-not-fat content of milk were not changed by the treatments. Milk fat content of the control(3.23%) was low compared with the treatment group(3.38%). Somatic cell count was reduced by 26.63% in the treatment. The results indicate that a sprinkler and fan cooling systems can provide an effective means to relieve heat stress and enhance productivity of lactating Holstein cows during hot and humid summer season.

• Journal of Animal Environmental Science
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• v.16 no.3
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• pp.193-204
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• 2010

The goal of this study was to develop a high-rise hog building(HRHB) for growing-fattening stages. HRHB was two story building and was suitable for specific environment in Korea. Manure was treated in a first floor and pigs were raised on the slatted second floor. Three ventilation systems - 1) duct inlet to wall exhaust system(V1), 2) eave inlet to wall exhaust system(V2), and 3) ceiling inlet to wall exhaust system(V3) - were used. This experiment was conducted during winter and from summer to fall. Air temperature, air speed, ammonia, hydrogen sulfide in HRHB, and swine growth rate were measured. During winter, air temperature in V1 system tended to be slightly high without any effect of outside air temperature. Maximum temperature from summer to fall was between 33.4 and $33.8^{\circ}C$ and there was no significant difference among systems. Continuously measured daily temperature was lower in V2 system than other systems and the fluctuation of air temperature was high. Air speed in V1 and V2 systems were similar (0.02~0.21 m/s), and was 0.04~0.15 m/s in V3 during winter. From summer to fall, air speed in V1, V2, and V3 systems were 0.10~0.41 m/s, 0.10~0.83 m/s, and 0.11~0.26 m/s, respectively. V2 system showed bigger fluctuation of air speed than other systems. During winter, the highest concentrations of ammonia in V1, V2, and V3 systems were 7.0, 3.5, and 8.7 ppm, respectively. Hydrogen sulfide was not detected. The highest concentrations of ammonia from summer to winter in V1, V2, and V3 systems were 6.1, 2.8, and 5.6 ppm, respectively. Swine growth showed no statistical significance among systems. However, daily weight gain was approximately 4% higher in V1 and V3 than in V2. Feed intake/daily weight gain was approximately 4% higher in V1 than other systems. From summer to fall, daily weight gain in V1 and V3 tended to approximately 3% higher than other systems, and feed intake/daily weight gain was approximately 2% higher in V1 than other systems. Hence, V2 system for the ventilation system of HRHB should not be utilized.

• Journal of Animal Environmental Science
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• v.13 no.3
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• pp.153-160
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• 2007

Study for the effect of three different microbial feed additives(henceforth MA-A, MA-B, and MA-C) on feed coversion rate, and physical and chemical characteristics of swine finisher was conducted. MA-B had higher number of Lactobacillus spp. and yeast, compared to any other. The amylase activity of MA-B was also higher than any other. The daily feed intake rates of pigs fed control, MA-A, MA-B and MA-C were 3.15, 3.14, 3.31 and 3.42 kg, respectively. MA-C had the highest weight gain. However, there was no significant difference between treatments. The weights of feces daily excreted by pigs fed control, MA-A, MA-B, and MA-C were 2.14, 2.02, 2.18, and 2.23 kg/day, respectively. The volume of urine daily excreted by pigs fed control, MA-A, MA-B, and MA-C were 3.14, 3.26, 3.27, and $3.41\;{\ell}/day$, respectively. Water content, T-N, $P_{2}O_{5}$, and $K_{2}O$ in swine manure were not significantly different between treatments. The BOD were between 42,576 and $67,450\;mg/{\ell}$ for feces and were between 5,882.5 and $8,657.5\;mg/{\ell}$ for urine, respectively. The SS were between 138,000 and $180,000\;mg/{\ell}$ for feces and were between 875.0 and $1450.0mg/{\ell}$ for urine, respectively.

• Journal of The Korean Society of Grassland and Forage Science
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• v.15 no.2
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• pp.132-139
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• 1995

This experiment was canied out to select the soybean of high productivity suited for soiling. and growth characterisitcs, palatability, dry matter and crude protein yield of 10 cultivars of soybean have been evaluated at the experimental forage field. College of Natural Science of Kon-Kuk University in Chungju over three years (1 989-1 09 1 ). The results obtained are summarized as follows: JangBaek showed the tallest plant length from the 70th day to 80th day during cultivation period. and BaekUn showed the tallest at 90th day. PalDal among all cultivars showed the fastest growth rate and the strongest resistant lodging during cultivation period. The stem diameter of 70th day showed highly in order of PalDal and HwangKeum > BaekUn > KwangKyo and JangYeob, the 80th day showed highly in the order of TogYu > BaekCheon > JangBaek and 90th day showed highly in order of BangSa > BaekCheon > JangYeob. Stem hardness was highly increased with increasing of cultivation period, but no significant difference were found among the soybean cultivan. Especially, BaekUn and TogYu of 90th day showed very high as 17.9 and 17.6 kg/cm2, respectively. In the number of branch, PalDal was the lowest during cultivation period(70, 80 and 90th day), and 90th day showed lower two and three times than other soybeans(P<0.05). In the leaf rate, BaekCheon showed the highest according to cultivation period and the lowest in JangBaek. The fresh yield was tended to increase by increasing cultivation period at all cultivars except KwangKyo, but no significant differences were found among cultivars. Dry matter yield of JangYeob was the highest as 5, 861 kg/ ha at 70th day, and that of KwangKyo and TogYu was the highest as 7, 471 and 10, 603 kgha at 80th and 90th day, respectively. Relative palatability of 70th days showed very high at all soybean cultivars(81-100%), and that of 80th and 90th day showed the highest at TogYu, while showed the lowest at PalDal. In crude protein content of the 70th, 80th and 90th day, DanYeob, JangYeob and HwangKeum were the highest as 20.1, 17.9 and 20.4 percentage, respectively. Crude protein yield during cultivation period showed the highest at JangYeob(7Oth : 1, 068, 80th : 1, 211, 90th : 1, 882 kglha), but showed the lowest at BangSa(70th : 61 1, 80th : 814, 90th : 1, 078 kg/ha).

• Journal of The Korean Society of Grassland and Forage Science
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• v.5 no.3
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• pp.207-211
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• 1985

This study was conducted to determine the effects of shade (full day light; 100, 80, 60, 40 and 20%) and fertilization levels (high; $N\;30kg-P_2O_5\;35kg-K_2O\;30kg$, moderate; $N\;20kg-P_2O_5\;25kg-K_2O\;20kg$, and low; $N\;10kg-P_2O_5\;15kg-K_2O\;10kg$) of forest pasture on intake palatability of Korean native goat, and the effects of shade under the conditions of 50% shaded forest pasture and full day light pastures on grazing behavior. This experiment was done at the experimental field of Chungnam National University, in Taejon, from 1983 to 1984. The results obtained are summarized as follows: 1. The dry matter intake, R.I.I. and Touch number of Korean native goat were affected by the shade degrees and fertilization levels, generally the increase of the fertilization level and high shading degree increased the NO_3-N$ contents in the plants, but decreased the soluble carbohydrate contents. It means that the decrease of the utilization of the shade culture grasses is due to the decreased intake palatability of forest pastures, particularly the conditions high fertilization level and above 60% of shading level seemed to have a nitrate stress. 2. Grazing time of forest pastures by Korean native goat tended to be spend more time than full day light pastures, also tendency of the major grazing activity tended to be graze continuously without difference of variation of grazing time within a day. Considering of the characteristies os shade, the intensive utilization of forest pastures seemed to be most effective during the high temperature season in August.

• Journal of The Korean Society of Grassland and Forage Science
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• v.36 no.2
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• pp.115-123
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• 2016

In this study, the effect of energy and protein ratio on the nutrient availability and body weight gain was determined to find the proper nutrient level for the stage of replacement dairy heifers before fertilization at approximately 12~24 months old after birth. Dry matter intake showed that the TDN/CP rate of T1 (5.0:1), T2 (4.5:1) and T3 (4.0:1) resulted in similar values. Among feces, the ash content of T1 was 11.07%, which was significantly (p < 0.05) higher than that of T3 (9.69%). It was also significantly (p < 0.05) higher than that of T2 (10.32%). When the TDN/CP rate was increased, the ash content in the feces was also increased. Regardless of the initial weight, weight gain was increased significantly as the CP rate in the feed was increased on the $30^{th}$ day. On the $60^{th}$ day, T2 showed the highest rate of gain (p < 0.05). As the TDN rate was decreased or the protein rate was increased, weight gain was significantly (p < 0.05) increased. Regarding GPT level in the blood after finishing the test, T1 and T3 (112.6, 88.3 u/l) showed significantly (p < 0.05) higher value than T2 (50.9 u/l). For phosphorus level, T1 (46.3 mg/dl) showed significantly (p < 0.05) higher value than other treatments. For HDL cholesterol level, T2 (145.2 mg/dl) had significantly (p < 0.05) higher level than T1 (121.0 mg/dl) or T3 (132.3 mg/dl). For triglyceride levels, T3 (40.6 mg/dl) had significantly (p < 0.05) higher value than T1 (20.7 mg/dl) and T2 (29.0 mg/dl). For other blood parameters including BUN concentration, there were no significant (p > 0.05) difference among treatments. As a result, although feed intake and weight gain with TDN/CP rate of 4:1 showed best results, considering the excess body fat accumulation possibilities or blood metabolism, it seems 4.5:1 ratio is most appropriate.

• Journal of The Korean Society of Grassland and Forage Science
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• v.33 no.4
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• pp.281-289
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• 2013

This study was conducted to investigate the effects of feeding seleniferous whole crop barley silage (WCBS) on the growth performance, blood and carcass characteristics, and tissue selenium deposition infinishing Hanwoo steers. A total of 20 growing Hanwoo steers were selected and assigned to one of the following feed groups: control (0.1 ppm Se), T1 (0.3 ppm Se), T2 (0.9 ppm Se), and T3 (0.9 ppm of inorganic Se). Five steers were allocated to each treatment group, and the trial lasted for 90 days. All experimental diets combined seleniferous and/or non-seleniferous WCBS up to a ratio of 30%. For the T3 diet, 0.9 ppm Se in the form of sodium selenite was added to the control diet. Dietary level and type of selenium did not affect feed intake and body weight gain. Blood total lipid and triglyceride concentrations were significantly (p<0.05) lower in the T2 group than in control. Blood immunoglobulin G concentration increased significantly (p<0.05) with increasing levels of dietary selenium; concentrations were significantly (p<0.05) higher in T2 and T3 than in control. Blood selenium concentration was the highest (p<0.05) in T2. No significant difference was observed in dressing rate, ribeye area, marbling score, meat color and fat color. Further, no association was found between levels and chemical form of dietary selenium and quality and quantity of meat. To the contrary, tissue selenium content in kidney, liver, and hind leg increased significantly (p<0.05) with increasing levels of selenium; however, feeding inorganic selenium did not introduce a significant increase in tissue selenium content of finishing Hanwoo steers. The results indicated that the selenium present in seleniferous WCBS was an effectively absorbable selenium source, suitable for increasing tissue selenium content in beef. Approximately 100 g of hind leg muscle from steers fed on the T2 diet met approximately 69% of the recommended daily selenium requirements.