• 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.

• Korean Journal of Poultry Science
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• v.48 no.4
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• pp.161-168
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• 2021

The present study investigated production traits, including body weight, egg production, egg weight, and egg quality in Korean indigenous parent stocks. Parent stocks produced from a nine-combination association from five pure line strains (C, D, F, K, and Y) were used. The body weight analyses results showed that the CY combination had the highest body weight (1,604.9 g) and the DK combination had the lowest (1,424.4 g). The average age at first egg of the nine combinations was 118.6 days; however, that of the YD combination was 111.6 days, making it the fastest growing combination, whereas the DK combination was the slowest, at 126 days. Hen-day egg production was 74% or more for the CF, CK, and DK combinations. The DK combination hens showed excellent persistence in egg laying. Hen-housed egg production exhibited results similar to those of hen-day egg production. Egg weight was significantly higher in the DK combination than in the other combinations and was observed to increase from 20 (43.9 g) to 40 (58.1 g) weeks. The egg quality analyses results showed that the combinations based on the F and K strains had a bright eggshell color, with relatively high egg weights. Eggshell strength and thickness were the highest in the DK combination (3.8 kg/cm², 0.38 mm). In summary, the CF and DK combinations showed excellent egg production ability and egg quality, while the YC, YD, and YK combinations with the Y strain as the paternal strain exhibited poor performance.

• Korean Journal of Poultry Science
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• v.47 no.4
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• pp.237-245
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• 2020

This study investigated the effects of breed, laying age, and egg storage period on hatching performance. Eggs were collected from early laying period (27 to 29 weeks old) and late laying period (50 to 52 weeks old) in Hwanggalsaek Jaeraejong, Korean Rhode Island Red, and Korean White Leghorn chicken breeds. Eggs laid for each period were stored for 3, 7 and 14 days and then hatched. Fertility, hatchability, and embryonic mortality were observed to determine the hatching performance. The results showed that hatching performance was affected by breed, laying age, and egg storage period with independently or interactively. The Korean Rhode Island Red breed had the lowest hatching performance. Hatchability and early embryonic mortality rate increased in early laying period eggs compared to the late laying period, but the late embryonic mortality rate increased in late laying period eggs. Additionally, hatching performance decreased as the egg storage period increased. Using breed-specific hatching management techniques, avoiding late laying period eggs, and shortening the egg storage period to seven days after laying may improve the hatching performance.

• Journal of Sericultural and Entomological Science
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• v.46 no.2
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• pp.54-57
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• 2004

A new silkworm variety "Buhungjam" for autumn rearing season is $F_1$ hybrid between Jam149, a japanese race bred from introduction breeding and Jam150, a chinese race from introduction breeding. Jam149, japanese parent of the "Buhungjam" showed high GCA in pupation percentage, cocoon shell percentage and filament length and Jam15, chinese parent showed high GCA in cocoon shell percentage and cocoon filament length. In the local adaptability test performed at 8 local areas in spring of 2003, Buhungjam records 7% higher in cocoon yield and 8% in raw silk yield than the check variety, Daesungjam.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2003.05a
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• pp.1-14
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• 2003

• KOREAN POULTRY JOURNAL
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• v.37 no.11 s.433
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• pp.143-145
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• 2005

• Korean Journal of Poultry Science
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• v.15 no.2
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• pp.167-184
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• 1988

종계나 채란계의 사육목적은 전산란기간중 더 많은 수의 달걀과 더욱 품질이 좋은 달걀을 얻는데 있다. 그러나 이들은 장시간 사육될 뿐만 아니라 발육단계별로 질병에 대한 감수성이나 질병에 의한 후유증이 다르기 때문에 질병관리는 그만큼 더 어려워진다, 왜냐하면 육추기때의 추백리나 전염성기관지염 또는 감보로병 등의 감염은 즉각적인 피해가 있을 수도 있지만 그 후유증은 산란기에 이르러서야 관찰되기 때문이다. (중략)

• KOREAN POULTRY JOURNAL
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• v.18 no.7 s.201
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• pp.91-96
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• 1986

닭의 산란능력에 영향을 미치는 요인들을 개괄하였으며 특히 바이러스성 질병에 대하여 논의하였다. 전염성질병은 예측할 수 없는 상황에서 발생하므로 질병의 발생을 방지할 수 있는 모든 방법들이 사전에 강구되어야만 한다. 최근들어 전염성기관염이 전국적으로 확산됨에 따라 채란계농가나 종계농가의 피해가 날로 높아가리라 사료되며, 우리 모두의 지혜를 모아 어려움을 슬기롭게 풀어가야 하리라 믿는다

• KOREAN POULTRY JOURNAL
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• v.25 no.11 s.289
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• pp.136-141
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• 1993

산란계나 종계의 육추, 육성, 성계기에 있어 체중이 낮은 병아리는 계군 전체의 평균체중을 끌어내릴 뿐 아니라 체력이 약하여 육성율, 생존율, 산란율을 저하시키는 주요원인이 되고 있다. 이같은 사실은 육계에서도 같은 결과를 보이고 있어 육계 농장에서의 질병과 관리 및 이에 따른 경제성 개선에 관한 내용을 실예를 들어 살펴보기로 한다.

• Korean Journal of Poultry Science
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• v.13 no.2
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• pp.173-178
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• 1986

Data on egg production, egg weight and egg mass were obtained from a sample of the Synthetic White Leghorn population which was raised at Poultry Breeding Farm, Seoul National University. Egg mass was not measured directly, but was calculated from the egg numbers and the average egg weight for same period. Phenotypic means, components of variance and covariance, heritabilities and genetic correlations were computed. Egg mass was estimated to be a lowly heritable trait (0.204-0.270). High heritability estimates were found for age at sexual maturity and egg weight. Genetic correlation estimates were high and positive between egg mass and egg number(combined estimates 0.711). Egg mass and egg weight were moderately correlated genetically (0.431). Genetic correlation estimates was -0.280 between egg number and age at sexual maturity, but was 0.524 between egg weight and age at sexual maturity. Results show that selection for total egg mass based on record from a single period will not be satisfactory unless the single period chosen is one in the latter part of the laying year.