• Korean Journal of Poultry Science
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• v.48 no.2
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• pp.91-100
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• 2021

The study determined the effects of stock density (SD) and energy level (EL) on growth performance, serum biochemistry, and meat quality in Korean native chickens. A total of 240 chickens were randomly assigned to one of the four treatments including two stock density (low, 14, and high, 16 chickens per m²) and two energy level (low, 2,950, 3,000, 3050 ME kcal/kg, and high 3,150, 3,200, 3,250 ME kcal/kg, for starter, grower, and finisher, respectively). During the whole period of the experiment, the chickens were fed ad libitum. The greater final body weight and weight gain were achieved in chickens fed high energy diet, whereas the final body weight and weight gain were significantly reduced in high-density treatment compared with the low density. Chickens in low-density groups had a higher feed intake compared with high-density treatment, however, the energy level did not affect the feed intake. An improved overall feed conversion ratio was detected in the high energy treatment. There was a significant interaction between stock density and energy level on cholesterol concentration. The concentration of aspartate transaminase in serum was increased by higher stock density. There was a significant treatment interaction on IgM levels. Moreover, the carcass rate was significantly increased in the high energy level treatment. Based on the findings, we suggest that rearing chickens in low density with high dietary energy levels could be beneficial by improving the growth performance.

• Korean Journal of Poultry Science
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• v.39 no.1
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• pp.71-76
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• 2012

This study was carried out to investigate the performance of growing period of two-crossbred of Korean Native Chickens. A total of four hundred eighty female 2-crossbred chicks that restored strains and were aboriginal at National Institute of Animal Science. Treatments were four crossbreds (4 replications/crossbred, 30 birds/replication) as A) C strain ${\times}$ S strain, B) C strain ${\times}$ H strain, C) R strain ${\times}$ S strain, and D) L strain ${\times}$ H strain, respectively. Livability of C crossbred was the highest as over 90% and that of B crossbred was the lowest as 73~78% during growing period (P<0.05). Body weight of A crossbred was the highest at the 4 week and that of D strain was the lowest at the 4 and 8 week (P<0.05). Weekly body weight of B and C crossbreds were higher than A and D crossbreds (P<0.05). There was no significant difference among four crossbreds. Weekly feed intake of D crossbred was the highest among all crossbreds at 0~4 weeks (P<0.05). These results suggested the basic data on the record of growing phase of 2-crossbreed Korean Native Chickens.

• Korean Journal of Poultry Science
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• v.39 no.2
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• pp.133-141
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• 2012

This study was carried out to investigate the performance of laying period of two-way crossbred of Korean native chickens. A total of four hundred eighty female 2-crossbred chicks that restored strains and were aboriginal at National Institute of Animal Science. Treatments were four crossbreds (4 replications/crossbred, 30 birds/replication) as A) C strain ${\times}$ S strain, B) C strain ${\times}$ H strain, C) R strain ${\times}$ S strain, and D) L strain ${\times}$ H strain, respectively. There were no significant difference on age, egg weight, and body weight at first egg among crossbreds (P>0.05). Body weight of D crossbred was lower compared to other crossbreds at the age of 24, 32, 40 and 60 week (P<0.05). Feed intake of A crossbred was highest among crossbreds (P<0.05). Weekly egg weight of A crossbred was the highest among crossbreds all laying period except 48~52 and 60~64 weeks. Hen-house egg production of A and B crossbreds was higher than that of C and D crossbreds (P<0.05). Hen-day egg production decreased after at the age of 36 weeks. Weekly egg production of A and B crossbreds was higher compared to C and D crossbreds (P<0.05). These results suggested the basic data on the record of laying period of 2-crossbreed Korean Native Chickens.

• Animal Bioscience
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• v.36 no.9
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• pp.1357-1366
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• 2023

Objective: This study aimed to identify the single-nucleotide polymorphisms (SNPs) in the dual-specificity phosphatase 8 (DUSP8) and insulin-like growth factor 2 (IGF2) genes and to explore their effects on inosine-5'-monophosphate (IMP), inosine, and hypoxanthine contents in Korean native chicken -red-brown line (KNC-R Line). Methods: A total sample of 284 (males, n = 127; females n = 157) and 230 (males, n = 106; females, n = 124) aged of 10 weeks old KNC-R line was used for genotyping of DUSP8 and IGF2 genes, respectively. One SNP (rs313443014 C>T) in DUSP8 gene and two SNPs (rs315806609A/G and rs313810945T/C) in IGF2 gene were used for genotyping by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and KASP methods, respectively. The Two-way analysis of variance of the R program was used to associate DUSP8 and IGF2 genotypes with nucleotide contents in KNC-R chickens. Results: The DUSP8 (rs313443014 C>T) was polymorphic in KNC-R line and showed three genotypes: CC, CT, and TT. The IGF2 gene (rs315806609A/G and rs313810945T/C) was also polymorphic and had three genotypes per SNP, including GG, AG, and AA for the SNP rs315806609A/G and genotypes: CC, CT, and TT for the SNP rs313810945T/C. Association resulted into a strong significant association (p<0.01) with IMP, inosine, and hypoxanthine. Moreover, the significant effect of sex (p<0.05) on nucleotide content was also observed. Conclusion: The SNPs in the DUSP8 and IGF2 genes might be used as genetic markers in the selection and production of chickens with highly flavored meat.

• Korean Journal of Poultry Science
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• v.32 no.2
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• pp.125-133
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• 2005

Morphometric changes in testicular Sertoli and Leydig cells from hatching to adulthood were studied using Korean native chickens of 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 21, 24, 28, 32, 44, 52 and 64 weeks (n=13 chickens per group) of age. The objective of this study was to understand the developmental phase of the Sertoli and Leydig cells with age. Testis of chickens was fixed by whole body perfusion using a fixative containing $2.5\%$ glutaraldehyde in cacodylate buffer, processed and embedded in Epon-araldite. Using 1 Um sections stained with methylene blue-azure II, qualitative and quantitative (stereological) morphological studies were performed. The average volume of a testis of 1 week old Korean native chickens was determined as $0.148\;cm^3$ and the parameter increased linearly from 1 week to 21 weeks days $(28.86\;cm^3)$, and did not change from 21 weeks to 64 weeks. The volume density of the seminiferous tubules increased with age from $32.6\%$ at week 1 to $92.89\%$ at week 64. The volume density of the interstitium represents $67.4\%$ of the testicular parenchyma at week 1. This proportion progressively diminished during development to reach a value of $7.11\%$ at week 64. The volume density of the Leydig cells decreased almost linearly from 1 week $(4.9\%)$ to 14 weeks $(1.7\%)$ and remained unchanged thereafter. In contrast, the Sertoli cells occupied a volume density of $3.4\%$ at week 1, increased progressively up to 18 weeks of age $(10.79\%)$ and remained unchanged thereafter. The absolute volume of the Leydig and Sertoli cells per testis increased significantly from week 1 to week 21 but did not change significantly from week 24 to week 64. The number of Leydig cells per testis increased almost linearly from 1 week to 21 weeks, remained high and unchanged with advancing age. The number of Sertoli cells per testis increased gradually with age from 1 week to 14 weeks and remained unchanged thereafter.

• Korean Journal of Poultry Science
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• v.48 no.3
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• pp.123-131
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• 2021

In this study, we investigated the effect of separate-sex and straight-run rearing system on the productivity of Korean native chickens. A total of 1,140 GSP-Hanhyup^® Korean native chickens were divided into male, female, and straight-run rearing groups, and the survival rate, body weight, feed intake, and feed conversion ratio were investigated from birth to 12 weeks of age. The average survival rate was 97.9%, and there were no significant differences among the groups. Body weight was significantly different among the groups at all weeks of age (P<0.01). After 4 weeks of age, the male group had the highest weight, followed by the straight-run group, and finally the female group. At 10 weeks, the most uniform body weight was shown in the female group (78%), while the lowest was in straight-run group (44%). Comparing the separate-sex and straight-run groups, male chickens were found to have higher body weights in the separate rearing group than in the straight-run group; however, there was little difference in those of female chickens. Feed intake was the highest in the male group, followed by the straight-run group, and lastly, the female group, while the feed conversion ratio had an opposite trend. Although there is little difference in the production performance of chickens between separate-sex rearing and straight-run rearing system, we concluded that the separate-sex rearing system is much more advantageous than the straight-run rearing system in terms of productivity due to group uniformity.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.11
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• pp.1546-1550
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• 2006

The purpose of this study was to assess the genetic variation and establish the relationship amongst breeds and strains using 15 chicken specific microsatellite markers. A total of 285 unrelated DNA samples from four Korean native chicken strains (Black strain of Korean native chicken; KL, Red Brown strain of Korean native chicken; KR, Ogol strain of Korean native chicken; KS and Yellow Brown strain of Korean native chicken; KY) and three introduced chicken breeds (F strain of White Leghorn; LF, K strain of White Leghorn; LK, Rhode Island Red; RC and Cornish; CN) were genotyped to estimate within and between breed genetic diversity indices. All the loci analyzed in 15 microsatellite markers showed a polymorphic pattern and the number of alleles ranged from 5 to 14. The polymorphism information content (PIC) of UMA1019 was the highest (0.872) and that of ADL0234 was the lowest (0.562). The expected total heterozygosity (He) within breed and mean number of observed alleles ranged from 0.540 (LF) to 0.689 (KY), and from 3.47 (LK) to 6.07 (KR), respectively. The genetic variation of KR and KY were the highest and the lowest within Korean native strains, respectively. The genetic distance results showed that Korean native chicken strains were separated with the three introduced chicken breeds clustered into another group. The lowest distance (0.149) was observed between the KR and KL breeds and the highest distance (0.855) between the KR and LK breeds. The microsatellite polymorphism data were shown to be useful for assessing the genetic relationship between Korean native strains and other foreign breeds.

• Agribusiness and Information Management
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• v.11 no.2
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• pp.25-34
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• 2019

Poultry is one of the three major meats in Korea and is a representative source of protein. The annual per capita consumption of chicken has been showing steady growth trends, with an increase of approximately 89% in 2018 compared to that of 2005. In this study, we investigated the domestic chicken production and consumption, and conducted an overall study on the domestic chicken industry. By using consumer panel data, we analyzed the characteristics of consumers buying chicken. Specifically, poultry was categorized into two types: traditional raw chicken and processed chicken, which emphasizes convenience. The purchase of raw chickens has generally been on the decline. From these, however, the proportion of native Korean chicken and chicken cuts is on the rise. Processed chicken, on the other hand, continues to grow, especially online. After examining the consumption characteristics of consumers who buy chicken, it was found that the purchase share increased with increasing age of native Korean chickens, whereas the purchase share increased with decreasing age of processed chicken. Based on these results, we confirmed that it is necessary to establish differentiated marketing and promotion strategies for each consumer target for the growth of chicken market.

• Food Science of Animal Resources
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• v.31 no.5
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• pp.684-692
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• 2011

The quality attributes of thigh meat from a certified meat-type commercial Korean native chicken (WoorimatdagTM, WM) and a commercial broiler (Ross, CB) raised under the same environmental conditions, were compared. One-d-old, mixedsex WM (200), and 200 broilers (Ross, CB) each were randomly assigned to floor pens (20 chickens per pen). The production stages (I, II, and III) were selected based on similar live weight. The crude fat contents of WM thigh meat were lower than those of CB. WM thigh meat contained higher stearic and arachidonic acid contents but lower palmitoleic and oleic acid contents compared to those of CB. The thigh meat color CIE $L^*$- and CIE $b^*$-values of WM were lower, but inosine-5'-monophosphate content was higher in WM than CB in whole production stages. WM thigh meat showed higher collagen content, hardness, springiness, gumminess, and chewiness than CB. In sensory evaluation, odor, taste, and overall acceptance were higher while color was lower in WM. Based on these results, it can be concluded that even if commercial broilers are raised under the same environmental conditions as WM, the unique quality attributes of WM thigh meat are distinctively unique.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.11
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• pp.1546-1552
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• 2002

Proliferation and differentiation of ovarian cells are regulated by gonadotrophins and various intraovarian factors, with many of their actions dependent on growth factors. Transforming growth factor-$\beta$ (TGF-$\beta$) has been reportedly involved in the regulation of ovarian follicular development. The overall objectives of the present study were to examine the influence of TGF-$\beta$1 expression in ovarian follicular development or yolk formation and to investigate the association of egg weight with ovarian TGF-$\beta$1 expression at 60 wk. Egg weights of 70 Korean Native Ogol Chicken (KNOC) were recorded from 20 to 60 wk. Ovaries were taken at 60 wk, and TGF-$\beta$1 was measured with ELISA, respectively. Based on egg weight up to 60 wk and TGF-$\beta$1 expression in ovary, the chickens were divided into high and low groups. Egg weights and follicle weight in the high TGF-$\beta$1 group were higher than those in the low groups. Also, TGF-$\beta$1 expression and follicle weight in high egg weight group were higher than those in the low groups. Taken together, the results indicate that TGF-$\beta$1 is associated with egg weight in KNOC. This association of TGF-$\beta$1 with egg weight in KNOC supports the report that TGF-$\beta$ is mainly involved in the development and differentiation of follicles in the poultry. Further studies about other endocrine factors related to yolk formation are required to fully understand the endocrine mechanism of egg weight in Korean Native Ogol Chickens.