• KOREAN POULTRY JOURNAL
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• v.6 no.9 s.59
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• pp.29-32
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• 1974

최근 가금학 분야의 연구 보고서들을 검토하여 보면 닭 사회에서 일어나는 여러 가지 행동현상과 이들이 산란 및 산육능력에 미치는 영향에 관하여 연구한 재미있는 논문들이 많다. 이러한 것들을 정리하여 소개하는 것도 양계관리에 도움이될 것으로 믿어 소개하는 바이다.

• Korean Journal of Poultry Science
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• v.17 no.1
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• pp.17-25
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• 1990

Data are presented concerning the effect of different seasons and sexes during the growing period on broier performance. Total 38, 451 broiler chickens were raised in spring, summer and winter and they were marketed at 6 or 7 weeks of age. Birds were alloted to l18 groups (240-360 birds per pen) and weighted at termination in order to determine variation in several economic traits between the sex groups. The results obtained were summarized as follows ： 1. Livability, body weights and feed requirements were improved you but there was no significant improvement in feed intake. 2. There was no difference in livability by seasons, but average final weights were ; 2, 320, 2, 238 and 2, 138 grams for spring, winter and summer, respectively, and feed requirements were ： 2.02, 2.01 and 2.04 for spring, winter, and summer, respectively.

• 종축개량
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• v.17 no.2
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• pp.57-60
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• 1995

카나다의 돼지개량에 대한 국가적 유전능력 평가는 산육능력(100kg의 등지방과 일령)과 모돈의 번식능력(총산자수)을 BLUP animal model(최선형 불변예상치 가축모형 : Best Linear Unbiased Predictor Animal Model)을 이용하여 정규적으로 평가하고 있다. 새로운 검정자료가 수집되어 질때마다 매번 BLUP평가가 이루어져 농장으로 제공된다. 현재의 유전능력 변화에 대한 추정가는 연간 등지방 두께 0.35mm와 100kg도달일령 1.5일이 향상되었다. 이것은 1985년 BLUP이 소개된 이전보다 등지방 $50\%$, 일령 20배 이상의 개량효과이다. 그 외에 모돈의 번식형질에 대한 개량은 계속적으로 연구가 진행되고 있으며 국가적 육종계획에는 도체와 육질에 대한 유전적 개량사업이 추진되고 있다.

• 종축개량
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• v.20 no.4
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• pp.12-22
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• 1998

• KOREAN POULTRY JOURNAL
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• v.24 no.4 s.270
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• pp.150-154
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• 1992

• Korean Journal of Poultry Science
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• v.48 no.4
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• pp.177-184
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• 2021

Sex identification in day-old chicks is essential in the poultry industry. Currently, the feather-sexing using a sex-linked inheritance is a chick sexing method used extensively in the poultry industry. For chicks produced by feather-sexing, all females are early-feathering (EF) chicks and all males are late-feathering (LF) chicks. Therefore, investigating the effects of EF and LF phenotypes on production traits of chickens is critical. The purpose of this study was to analyze and compare the production performance between EF and LF chickens in Korean native commercial chickens. The results showed that the survival rate of the EF chickens was significantly higher than that of the LF chickens, from hatching to 12 weeks of age (P<0.05), with the highest difference observed in females. However, no significant difference was observed in body weight between the EF and LF chickens at almost all ages. In addition, no significant difference was observed between in feed utility, such as average daily feed intake and feed conversion ratio, between the EF and LF groups. In conclusion, although the survival rate of early-feathering chickens was superior to that of late-feathering chickens, no significant difference was observed in growth performance and feed utility among Korean native chickens. The results suggest that production capacity is not influenced by feathering type in the establishment of a breeder structure and production system for feather-sexing Korean native chickens, which is valuable for the practical application of feather-sexing in the poultry industry.

• Journal of Animal Science and Technology
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• v.49 no.3
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• pp.303-308
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• 2007

In order to investigate the relation of production traits and reproduction traits the data from Gyungnam heugdon(Berkshire) were analyzed. Pearson correlation coefficients of the reproductive traits including days to first farrowing, days to first breeding and no. of breeding for first litter with back fat thickness were ranged -.24 to -.26. Estimates of heritability and genetic correlation for the reproductive traits including days to first farrowing, days to first breeding and no. of breeding for first litter showed frequent and wide fluctuation due to lack of reproductive records. Pearson correlation coefficients of back fat with litter traits were low, but genetic correlation coefficients were relatively high. Genetic correlation coefficients of back fat with total litter size, pigs born alive, litter weight at birth and litter weight at weaning were .21, .24, .11 and .07 respectively. It suggests that thin back fat thickness deteriorates performance of litter traits. Genetic correlation coefficients of days to 90kg with total litter size, pigs born alive, litter weight at birth and litter weight at weaning were .14, .17, .09 and .00 respectively. This result imply that genetic improvement on the production traits reduce the litter trait performance.

• Journal of Embryo Transfer
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• v.22 no.3
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• pp.143-147
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• 2007

Records on 546 Korea native pigs for average daily gain (ADG), age at 70 kg (D70 kg) and backfat thickness (BF) made between 2001 and 2006 in herds on National Institutes of Animal Science in Korea were used to estimate genetic parameters. The data was analyzed by the DF-REML (Derivative-Free Restricted Maximum Likelihood) program of Boldman using a single-trait animal model. Heritabilities were 0.26, 0.09, and 0.29 for ADG, D70 kg and BF, respectively. The phenotypic correlations of ADG with D70 kg and BF were -0.71 and 0.30. The phenotypic correlation of D70 kg with BF was -0.15. The genetic correlations of ADG with D70 kg and BF were -0.11, 0.41, respectively. The genetic correlation of D70 kg with BF was -0.16. The data of weights and measurements on body length, body height and chest width after age at 11 months (days to 330) were shown scarcely less differences compare to data of age at 11 months.

• Korean Journal of Poultry Science
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• v.49 no.2
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• pp.89-98
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• 2022

This study compared the production and physiological characteristics of male and female Korean native commercial chickens. We investigated the growth performance, vitality, and stress response of 479 male and 608 female chickens from 1 d to 12 weeks of age. The body weight, feed consumption and feed conversion ratio were measured as growth performance. The survival rate, amount of telomeric DNA, DNA damage rate, heterophil-lymphocyte ratio (H/L ratio), and heat shock protein (HSP)-70, HSP-90α, and HSP-90β gene expression levels were analyzed as indicators of vitality and stress response. Body weight was significantly higher in male chickens than in female chickens after 2 weeks of age (P<0.01). Feed intake was higher in male chickens than in female chickens, whereas the feed conversion ratio showed the opposite trend. The survival rate was significantly higher in female chickens than in male chickens (82.8% vs. 73.8%, P<0.05). Stress response analysis revealed no differences between male and female chickens in terms of telomeric DNA content, DNA damage rate, H/L ratio, and HSP gene expression levels. Taken together, it was concluded that there was a significant difference in the growth performance and survival rate between male and female Korean native commercial chickens, whereas there was no difference in the degree of stress response between them. Therefore, in terms of the productivity of Korean native commercial chickens, it is judged that separate-sex rearing is much more advantageous than mixed rearing, regardless of the physiological characteristics of males and females.

• Korean Journal of Poultry Science
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• v.46 no.2
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• pp.105-115
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• 2019

In this study, viability, growth performance and egg production performance were investigated to determine the productive characteristics of 12 Korean domestic chicken varieties which have been collected and conserved for over 25 years in National Institute of Animal Science, Rural Development Administration, Korea. The 1,134 hens were tested and their production traits including survival rate, body weight, age at first egg laying, hen-day and hen-housed egg production, egg weight, and egg quality were measured. Survival rate was the highest in Korean Rhode-D and Korean Native Chicken (KNC) White and the lowest in Korean Cornish Brown (92.2% and 54.3%, respectively). Body weights from 4 to 50 wks were consistently high in the order of Korean Cornish, Korean Rhode, KNC, Korean Ogye, and Korean Leghorn breeds. There was no significant difference in weight between varieties within a breed. Age at first egg laying was the shortest in Korean Leghorn, while it was the longest in Korean Cornish. The hen-day egg production from $1^{st}$ egg to 57 wks was the highest in Korean Leghorn-K, and the lowest in Korean Cornish Brown. Egg weight was the heaviest in Korean Leghorn-F and the lightest in KNC White. The Haugh unit was the highest in Korean Rhode-C and the lowest in Korean Ogye. Taken together, these results suggest that it is desirable that the Korean Cornish variety is improved as the Korean meat breed because of its excellent growth ability, the Korean Leghorn variety is improved as the Korean layer breed because of its good laying performance, and the Korean Rhode and KNC varieties are improved as strong viable breeds because of their good survival rate.