• Korean Journal of Poultry Science
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• v.30 no.2
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• pp.101-106
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• 2003

In order to study the optimum daily protein allowance for broiler breeders of 24 to 64 weeks of age on a control-fed basis, an experiment was carried out with 400 hens of Arbor Acres strain. Four levels of protein allowances were used to supply 18 to 24g of protein per day in 2g increments. As the age of hens increased, a same stepwise increase and decrease in daily energy allotment was used in all treatments. Same amount of calcium, phosphorus, methionine and lysine were supplied in all treatments and throughout laying period. Hen-day egg production was highest in hens receiving 20g protein per day(p<0.05), but there was no significant difference among those fed daily protein ranging 18 to 22g, and increasing the daily protein allotment up to 24g resulted in a significant decrease(p<0.05). Average egg weight showed a trend to increase as the daily protein allowance increase(p<0.05), but no significant difference was found among the hens fed daily protein 20 to 24g. Feed and ME conversion was superior in hens receiving 20g daily protein(p<0.05). CP conversion was increased as the daily protein allowance increase(p<0.05), but there was no significant difference between hens receiving 18 and 20g daily protein. Feed cost required per egg or per kg egg was lowest in hens fed 20g daily protein. It could be concluded that the optimum daily protein allowance was 20g in all performances.

• Korean Journal of Poultry Science
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• v.30 no.1
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• pp.1-10
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• 2003

The objects of this study were to develop a new strain which has resistance to fowl typhoid, high performance in laying, and producing brown shell eggs favored by domestic consumers. Several White Leghorn (WL) breeds known as possessing genetic resistance to fowl typhoid and several brown shell egg breeds such as susceptible to the disease were used to produce the controlled strains with cross mating between the strains within the breeds and the experimental strains with crossbreeding between the breeds. The crossbred strains were Chungnong(CN) 21, 22, 23, 24, 25 and 26. The controlled strains were ISA brown CC, Hyline brown CC and Lohman brown CC. The survival rates were 99.95% for chicks of age 0∼l7 weeks and 91% for adult chickens of age 18∼72 weeks. There was no difference in survival rate between the crossbred and the controlled strains. The means of age of lst egg laying were 147 to 148 days and no difference was observed between the crossbred and the controlled. The egg Production rates of a9e 18∼72 weeks were 83.76% far the crossbred strains and 77.82% for the controlled strains, which is significantly higher in the crossbred than controlled strains by 6%. The numbers of the hen housed egg Production of age 18∼72 weeks were 292.33 eggs for the crossbred strains and 271.31 eggs fur the controlled strains. The difference of 21 eggs more produced by the crossbred than by the controlled was statistically significant. The mean egg weights of age 18∼72 weeks were 64.32g for the crossbred strains and 60.73g for the controlled strains, and the difference of 3.59g was statistically significant. The feed conversion rates during the age of 18 to 72 weeks were 2.297 for the crossbred strains and 2.454 for the controlled strains. The crossbreds were reduced feed consumption by 157g for 1kg of egg Production which was statistically significant. Haugh unit(H$.$u) at the age of 72 weeks were 82.20 for the crossbred strains and 77.82 for the controlled strains. The crossbred strains were superior quality by 4.38 H$.$u. There were no significant differences in the yolk color and the eggshell thickness between the crossbred strains and the controlled strains. The eggshell color of the crossbred strains was light brown which is the medium color of the white eggshell strains and the brown eggshell strains. The body weights at the ages of 8, 12, 18, 42 and 71 weeks were not different between the crossbred strains and the controlled strains.

• The Korean Journal of Pesticide Science
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• v.8 no.1
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• pp.54-62
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• 2004

The selective toxicity of spirodiclofen and fluacrypyrim+tetradifon to the predatory mite, Phytoseiulus persimilis and the tea red spider mite, Tetranychus kanzawai was evaluated. The bean leaf discs with adult females or eggs of both species were sprayed with several concentrations of spirodiclofen or fluacrypyrim+tetradifon. Spirodiclofen and fluacrypyrim+tetradifon were much less toxic to P. persimilis than to T. kanzawai. Although the survival rate of adult females of P. persimilis tended to decrease with increasing concentrations of spirodiclofen, 92-68% of predators survived at concentrations of 22.5-180 ppm. Likewise, reproduction was reduced with increasing spirodiclofen concentration. Spirodiclofen did not affect the hatch of P. persimilis eggs. Survival of immature predators decreased with increasing spirodiclofen concentration, however, 88-20% of immature predators reached adulthood at 22.5-90 ppm. In the case of fluacrypyrim+tetradifon, the survival rate of adult females of P. persimilis tended to decrease with increasing concentrations of fluacrypyrim+tetradifon. However, 94-72% of predators remained alive at concentrations of 22.5-180 ppm. Likewise, reproduction was reduced with increasing fluacrypyrim+tetradifon concentration. Fluracypyrim+tetradifon did not affect the hatch of P. persimilis eggs. Survival of immature predators decreased with increasing fluacrypyrim+tetradifon concentration, however, 100-86% of immature predators reached adulthood at 22.5-180 ppm. Based on the results, spirodiclofen and fluacrypyrim+tetradifon appeared to be promising candidates for use in integrated mite management programs where P. persimilis is the major natural enemy.

• Korean Journal of Environmental Biology
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• v.38 no.2
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• pp.323-331
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• 2020

The method of natural spawning is very passive and inconvenient for the study of developmental engineering in marine medaka, Oryzias dancena. The optimum concentration of human chorionic gonadotropin (HCG) and carp pituitary extract (CPE) for ovulation and spawning, and the injection time for the artificial spawning of marine medaka were analyzed in this study. The success rate, survival rate, and hatching rate were highest with 100IU HCG kg^-1 BW and 5mg CPE L^-1 in both male and female marine medaka (p<0.05). After obtaining unfertilized eggs and sperm by the injection of HCG and CPE into the broodstock of marine medaka, artificial fertilization could be successfully achieved any time fertilized eggs are needed in this species. This result should be useful for developing a study program for marine medaka as an experimental animal.

• Korean Journal of Poultry Science
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• v.41 no.2
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• pp.93-98
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• 2014

This study was conducted to analysis the reason for implementing HACCP system, advantage and disadvantage of HACCP system implemented laying hen farm. The study was carried out by randomly selected fifteen laying hen farms located in all around Korea. All data were collected from fifteen laying hen farms before and after the implementation of HACCP system. The results were as follows: The egg production rate, livability rate and monthly used animal medicine fee did not changed after HACCP system implementation. However, monthly used disinfectant fee tended to be higher in HACCP farm compared to non-HACCP farm. 26.92% of the laying hen farmer responded enhancement of their farm competitiveness as the major propose for implementing HACCP system. The advantages of HACCP implemented laying hen farms were methodical farm management (22.39%), improvement of awareness (21.18%), improvement of the farm sanitation management level (15.30%), safety egg production (15.05%), productivity enhancement (7.29%), reduction of mortality rate (6.82%), and improvement of labor's welfare (5.89%). The disadvantages of HACCP implemented laying hen farms were HACCP recording (43.30%), alteration of consciousness (22.60%), HACCP monitoring (11.11%), HACCP education (9.97%), HACCP verification (6.90%), and A high turnover of labor (6.13%). In conclusion, implementation of HACCP system to laying hen farm did not affect on the productivity or the use of animal medicine. However, the HACCP system may enhance safety and sanitation of egg production for consumer.

• Korean journal of applied entomology
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• v.35 no.3
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• pp.266-272
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• 1996

The selective tox\ulcornercity of fenpyroximate to the predatory mite Amblyseius womersleyi and the twospotted spider mite Tetranychus urticae was evaluated. Adult females and eggs of both species were placed on bean leaf dis~sd ipped in several concentrations of fenpyroximate. Fenpyroximate was much less toxic to A. womersleyi than to T. urticae. Although the survival of adult females of A. womersleyi tended to decrease with increasing fenpyroximate concentration, 58-74% of predators remained alive at concentrations of 6.25-50 ppm. However, reproduction of predators was not significantly reduced at any of the concentrations tested. At 6.25-50 ppm, 32-40% of twospotted spider mite adult females survived but all survivors were immobilized. Moreover, reproduction of twospotted spider mites was reduced with increasing fenpyroximate concentration. Fenpyroximate did not affect the hatch of A. womersleyi eggs or the development of immature predators. Although survival of immature predators decreased with increasing fenpyroximate concentration, 16-48% of immature predators reached adulthood at 6.25-50 ppm. However, all immature spider mites failed to develop to adulthood at 6.25-50 ppm. Adult female predators survived on a diet of twospotted spider mites intoxicated with fenpyroximate, and their fecundity and sex-ratio of the progeny were not substantially affected. Fenpyroximate at selective sublethal concentrations (6.25-12.5 ppm), therefore, could be of value in adjusting predatorlprey ratio in integrated management of twospotted spider mites.

• The Korean Journal of Pesticide Science
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• v.12 no.3
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• pp.249-255
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• 2008

The comparative toxicity of recommended rates of three acaricides, fluacrypyrim, cyflumetofen and spiromesifen to the predatory mite, Neoseiulus womersleyi and its prey, Tetranychus urticae was bioassayed in the laboratory. Fluacrypyrim and cyflumetofen were much less toxic to adult females of N. womersleyi than to those of T. urticae. Adult female predators treated with these two acaricides produced $88{\sim}93%$ as many eggs as did control females. Fluacrypyrim and cyflumetofen did not affect the hatch of N. womersleyi eggs or the development of surviving immature predators, and $92{\sim}96%$ of immature predators reached adulthood. Spiromesifen at its treated concentration did not significantly affect the survival and reproduction of adult female predators but caused 100% mortality in larvae of N. womersleyi. Adult female predators survived on a diet of spider mites treated with fluacrypyrim and cyflumetofen, and their fecundity was not significantly affected. Moreover, immature predators developed normally on prey treated with these two acaricides. The results indicate that fluacrypyrim and cyflumetofen are promising candidates for use in integrated mite management programs where N womersleyi is the major natural enemy.

• Korean Journal of Poultry Science
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• v.16 no.4
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• pp.239-252
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• 1989

The present study was carried out to investigate the improvement of major production traits with the published data of twenty-two years'random sample tests held in Korea from 1966 to 1988. Eight traits-roaring viability, laying viability, age of sexual maturity, hen day egg production, hen-housed egg production, egg weight, feed requirement, 500 days body weight-were dealt with in this study. The results obtained in this study are summerized as follows； 1. Total mean value for rearing viability was 99.4% in 1980s. Mean value for rearing viability of colored hen was 99.5% and white hen was 99.06% in 1980s. Mean value for laying viability was increased by 0.98%, 0.86% and 0.86% per year in pool data, white hen and colored hen, respectively. 2, Age of sexual maturity was decreased from 171.1 day to 160.8 day in pool data during 1960s- 1910s but increased to 162.4 day in 1980s； and decreased from 160.5 day to 1595 nay in white hen but increased from 163.7 day to 166.1 day in colored hen during 1970s-1980s. 3. Mean values for hen-day egg production were increased by 0.96%, 1.09% and 0.63% per year in pool data, colored hen and white hen, respectively. 4. Mean values for hen housed egg production were increased by 45, 5.37 and 4.23 per year in pool data, colored hen and white hen, respectively. 5. Egg weight were improved by 0.22g and 0.25g per year in pool data and colored hen but decreased by 0.03g in white hen. 6. feed requirement were improved by 0.04, 0.05 and 0.1 per year in pool data, white hen and colored hen, respectively. 7. 500 days body weights were increased by 0.38g per year in pool data but decreased by 14.95g and 10.37g in colored hen and white hen, respectively. 8. Estimate of correlation coefficient between age of sexual maturity and other factors such as hen day egg production. hen housed egg production, egg weight and 500 days body weight were -0.4512, -0.2876, -0.4376 and 0.2045 in pool data； -0.358, -0.1530 0.3475 and 0.1208 in white hen； 0.0989, 0.1181, 0.2885 and 0.2248 in colored hen, respectively. Estimates of correlation coefficient between hen day egg production and egg weight were 0.6233, -0.2259 and 0.2973 in Pool data, white hen and colored hen； between hen day egg production and 500 days body weight, 0.2417, 0.0774, -0.4787 ： between hen-housed egg production and egg weight, 0.6171, -0.2706, 0.4579： between hen housed egg production and 500 days body weight, 0.3082, -0.0792, -0.3368： between egg weight and 500 days body weight, 0.2742, 0.2205, 0.1354, respectively.

• Korean journal of applied entomology
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• v.53 no.3
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• pp.311-315
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• 2014

Lantern fly(Lycorma delicatula) is a major invasive pest that causes withering symptom of agricultural crops by sucking tree sap and sooty mold symptom by producing honeydew. This study was conducted to investigate the occurrence pattern of lantern fly in grape orchards in Gyeonggi area and the effect of winter temperature on L. delicatula egg survival during 2010 to 2013. In Gyeonggi areas, overwintered L. delicatula eggs began to hatch from early May and nymphs peaked in mid May. Adults emerged from late July and laid eggs until early November. The survival of L. delicatula eggs during overwintering was largely affected by winter temperatures. The relationship between the number of days below a threshold temperature (x) in January and the survival rate of overwintering L. delicatula eggs (y) was using linear regression model. The best model selected by the lowest RSS (residual sum of square) between predicted and actual survival was y = -1.0486 x + 94.496 ($R^2=0.7067$) with $-11^{\circ}C$ of threshold temperature. These results should be helpful to conduct L. delicatula management programs, since the results provided relivable prediction for the winter survival of L. delicatula eggs and the phenology of egg hatch in the spring.

• Journal of Aquaculture
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• v.13 no.3
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• pp.197-206
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• 2000

At the Poryoung coast, the spawning season of the mullet, Chelon lauvergnii lasts from May to June. A combination of rotifer, Rotifer nauplii and synthetic feed supported significantly (P < 0.05) better survival and growth of 1-day old mullet larvae during 70-day rearing experiment than the other feeds consisting of rotifer or rotifer + Artemia nauplii. Significantly higher growth and survival were also observed, when the larvae were fed on rotifer, that were harvested from culture enriched with masimaTR, or Artemia nauplii from culture enriched with cuttlefish liver oil, At the feeding density of 97-98 individuals /200 l, the mullet larvae displayed maximum growth and survival in aquarium each with 100 larvae /200 l.