• Korean Journal of Poultry Science
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• v.12 no.2
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• pp.59-64
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• 1985

The study was carried out to determine if a difference in initial chick weight was still evident in market body weight(6 or 8 week body weight) of broilers. The data of a total of 800 broiler commercial chick raised at Poultry Breeding Farm, Seoul National University from Aug. 6, 1981 to Oct. 1, 1981 were analysed. The results were summarized as follows: 1. Although the initial chick weight was about the same, male chick grew more rapidly than female and sex difference was the most striking factor in growth rate of broiler in this analysis. 2. The relationship between initial chick weight and body weight after hatching was decreased to the increase of weeks of age in both sexes. Though the correlation coefficients of the 6 week and 8 week body weight to the initial chick weight were 0.15 & 0.15 in female and 0.18 & 0.17 in male, the relationship was highly significant in both sexes. 3. Regressions of 6 and 8 week body weight on the initial chick weight in both sexes indicate that, for each increase of one gram in weight of chick at hatching, the average increase in body weight was 8.33 gram ＆ 10.07 gram in female and 7.85 gram ＆ 11.28 gram in male. Results show that the initial chick weight (1 day of age) influence average body weight of commercial broiler at 6 and 8 weeks of age.

• 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.

• Korean Journal of Poultry Science
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• v.7 no.1
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• pp.31-42
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• 1980

In order to identify the best superior cross combination of breeder stocks for broiler production, combining ability test and analyses of phenotypic performances for parent stocks were examined on records of 1,440 broiler chicken which were produced from 4 parental strains and 3 maternal strains at Hanhyup Poultry Breeding Farm from September 28, 1978 to January 5, 1979. The results obtained were as follows; 1. There was not found heterosis effect in viability but it seems to be desirable to select Hubbard strain in paternal line to improve viability. 2. As the paternal and maternal lines, selection of Ross strain showed the best paternal and maternal performance and the best general combining ability in body weight at 8 weeks of age is expected to be able to improve body weight of it s crossbred And the most superior cross combinations based on the specific combining ability and performance of rack crossbred were identified as Hubbard x Ross ana Ross x Hypeco crossbreds. 3. The best paternal and maternal lines on the smallest feed consumption for 8 weeks were Hubbard and Ross strains, and Hypeco strain, respectively. Especially Hubbard x Hypeco cross combination was proved as the smallest feed consumption compared with other cross combinations. 4. In feed requirement per Kg body weight increase, Hubbard strain for paternal line, Hypeco strain for naternal line, and cross combinations of Hubbard x Hypeco, Hubbard x Ross and Ross x Hypeco were certified as the most superiors. 5. Also superior cross combinations of Hubbard x Hypeco and Hubbard x Ross earned the most profit per bird through economic analysis. According to results as shown above, this experiment seems to be able to reach a such conclusion that production of superior cross combinations Hubbard x Ross, Hubbard x Hypeco and Ross x Hypeco through selection of Ross and Hubbard strains to paternal line and Hypeco and Ross strains for maternal line may become to considerable improvement for important economic characters of broiler; viability, body weight, feed consumption and feed requirement.

• Korean Journal of Poultry Science
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• v.49 no.4
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• pp.211-220
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• 2022

Poultry are exposed to extremely high levels of oxidative stress as a consequence of the excessive production of reactive oxygen species (ROS) induced by endogenous and exogenous stressors, such as high-stocking densities, thermal stress, environmental and feed contamination, along with factors associated with intensive breeding systems. Oxidative stress promotes lipid peroxidation, DNA damage, and inflammation, which can have detrimental effects on the health of birds. During the course of evolution, birds have developed antioxidant defense mechanisms that contribute to maintaining homeostasis when exposed to endogenous and exogenous stressors. The primary antioxidant defense systems are enzymatic and non-enzymatic in nature and play roles in protecting cells from ROS attack. Recently, plant flavonoids, which have been established to reduce oxidative stress, have been attracting considerable attention as potential feed additives. Flavonoids are a group of polyphenolic compounds that can be stabilized by binding structural compounds with ROS, and can promote the elimination of ROS by inducing the expression of antioxidant enzymes. However, although flavonoids can contribute to reducing lipid peroxidation and thereby enhance the antioxidant capacity of birds, they have low solubility in the gastrointestinal tract, and consequently, it is necessary to develop a delivery technology that can facilitate the effect intestinal absorption of these compounds. Furthermore, it is important to determine the dietary levels of flavonoids by assessing the exact antioxidant effects in the gastrointestinal tract wherein the concentrations of dietary flavonoids are highest. It is also necessary to examine the expression of transcriptional factors and vitagenes associated with the efficient antioxidant effects induced by flavonoids. It is anticipated that the application of flavonoids as natural antioxidants will become a particularly important field in the poultry industry.

• Korean Journal of Poultry Science
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• v.45 no.3
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• pp.175-182
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• 2018

The carcass and meat quality of new native chicken strains (A, C, and D) being developed in the Golden Seed Project for Samgyetang were compared with a commercial native chicken (Hanhyup No. 3, H) and Baeksemi (white semi broiler, W) strains. In total, 250 male chicks were raised under the same feeding and raising conditions for 5 weeks. After slaughter, the carcass weight and percentage yield of parts from each strain were measured and the physicochemical quality traits (general composition, color values, fatty acid composition, and sensory evaluation) of breast muscles were comparatively analyzed. The carcass weight (875.10 g) of the W strain was significantly heavier than that of the other native chicken strains, while that of A strain (537.54 g) was the lowest. The percentage yield of breast meat was also higher in the W strain than in the other strains. The fat content of W strain was higher than that of the other native chicken strains. The new native chicken strains (A, C, D) had higher contents of linoleic acid (C18:2) than the H strain. The A and D strains especially showed relatively high content of arachidonic acid (C20:4), a characteristic fatty acid in native chicken meats. On the other hand, the fatty acid composition of C strain was similar to that of the W strain. This study provides important information on specific quality characteristics than can be used to select new native chicken lines for breeding program.

• Korean Journal of Poultry Science
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• v.28 no.3
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• pp.267-274
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• 2001

The pineal gland of the bird occupies a key position in the phylogenetic evolution of this organ. Therefore, the purpose of this study was to investigate the developmental changes of the pineal gland during post-hatching period in Korean pheasant. The pheasants were sacrificed at 1-day-, 1-month-, 2-month-, and 6-month-old after hatching. The morphological characteristics of a pineal glands were determined in all pheasants using light microscope, and transmission electron microscope. Connective tissue originated from the capsule divided the pineal parenchyma into incomplete lobules. The parenchyma was consisted of pinealocytes and supportive cells. These parenchymal cells were arranged in the forms of solid lobules as well as incomplete follicles. At the follicular lumen, membraneous lamellar complexes and blob -like structures were present. Pinealocyte, a predominent cell type, had euchromatic nucleus, and showed the segmental organization. The bulbous apical portion had scanty free ribosomes and occasional cilia associated with basal bodies. The constricted neck, transitional portion from apical to pericarya had junctional complexes with adjacent supportive cells, and had microtubules. Cell body contained abundant mitochondria, well-developed Golgi complex, rough endoplasmic reticulum (RER) and free ribosomes. Basal processes extended from the base of the cell soma toward the basal lamina and contained 60∼90 nm dense cored vesicles. Supportive cells, another major type of the parenchyma, were characterized by the dense and elongated nucleus, and contained moderate number of mitochondria, RER, developed Golgi complex, free ribosomes and a few dense bodies in the perinuclear cytoplasm. Slender processes of supportive cells interposed between the pinealocytes and often bordered the basal region of the parenchyma. These results indicate that the pinealocytes of the pheasant are not rudimentary photoreceptor cells, and appear to have secretory function. Further studies will be required to confirm the morphological characteristics of pineal gland in adult pheasant during breeding and nonbreeding season.

• Korean Journal of Poultry Science
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• v.17 no.4
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• pp.255-268
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• 1990

This study was carried out to investigate the time-trends of genetic parameters of the dosed flock population which selected for improving egg production. Data for two layer pure lines, Line-W (Single Comb White Leghorn) and Line-B (brown layer) which have been maintained at the Mani Breeding Farm were collected from 1980 to 1985 during 5 generations. The effective number of parents per generation ranged from 148 to 366 in Line-W and 85 to 355 in Line-B, and the cumulative expected inbreeding coefficients during 5 generations of selection were 15％ and 1.6％. So inbreeding could not be considered a critical factor on estimating the genetic parameters, heritabilities and genetic correlations Heritabilities of EN 300 and EN 400, primary two selected traits were significantly decreased during 5 generations but the estimates of the other 03its not showed the consistent decreasing pattern significantly. No time trends of probable consequence were evident in the genetic correlation coefficients of the traits studied. The reason for that situation was attributed to the fact that selection was conducted for multiple objectives and the relative importance of selection for the studied traits were not consistent by generations.

• Korean Journal of Poultry Science
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• v.42 no.4
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• pp.315-325
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• 2015

Recently, livestock breeding is more focused on the meat quality rather than meat quantity, mainly due to the improvement of consumers' income. Among the meat quality traits, meat color is one of very important traits because meat color is the first selection criterion from the consumers in the market. Most of the economically important traits have continuous variations and these are called quantitative traits. the genomic locations affecting these traits are called quantitative trait locus (QTL), which is mostly controlled by many genes having small effects. In this study, the recent QTL and candidate gene studies were reviewed in order to meet the consumers' demand for the future market. In the chicken QTL database, three traits are related with meat colors, namely breast color (Bco), meat color (Mco), drip loss (DL) and pH. The identified number of QTLs is 33 from 13 chromosomal regions. In these QTL regions, 14 candidate genes were identified; Eight for meat color (APP, BCMO1, COL1A2, FTO, KPNA2, PSMD12, G0S2, FTSJ3), two for drip loss (AGRP, FTO) and four for pH (GALNT1, PCDH19, DIAPH1, SPP2). These QTLs and candidate genes need to be confirmed and fine mapping is ultimately needed for identification of causative variations. The recently developed chicken resource population using Korean native chicken can be used for the improvement of meat quality traits, which increase the value that needed in the chicken industry.

• Korean Journal of Veterinary Service
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• v.31 no.1
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• pp.161-166
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• 2008

Deep pectoral myopathy (DPM), also known as Oregon muscle disease or green muscle disease, was first described in 1968 by Dickinson et al as "degenerative myopathy" in turkeys. Even though this condition was first recognized in adult meat-type turkey and chicken breeders, it is becoming more and more common in meat-type growing birds. DPM occurs exclusively in birds that have been specially selected for breast muscle development. It is generally recognized that DPM is an ischemic necrosis that develops in the deep pectoral muscle (supracoracoideus or pectoralis minor muscle) mainly because this muscle is surrounded by inelastic fascia and the sternum, which do not allow the muscle mass to swell in response to the physiological changes occurring when muscle are exercised, as in wing flapping. The lesion does not impair the general health of birds and is generally found during cut-up and deboning, moreover, it can be both unilateral or bilateral, affecting just one or both pectoralis minor muscle, respectively. No public health significance is associated to DPM, but it is aesthetically undesirable. The fillet should be removed, whereas the rest of the carcass is still fit for human consumption. However, the required trimming operations determine the downgrading of the products and produce an economic loss for the industry, especially because it affects the more valuable part of the carcass. The incidence of DPM increases with market weight in broilers, with more cases reported in higher-yielding strains and in males. Increased bird activity (flock nervousness, flightiness, struggle, and wing flapping) induced by factors such as feed or water outages, lighting programs and intensity, human activity, and excessive noises in and around chicken houses should be looked at as a trigger for the development of DPM in broiler. However, most of the studies conducted to evaluate the incidence of DPM in poultry are concerned with parental commercial breeding stocks under experimental conditions (Bianchi et al. 2006. Poult Sci 85 : 1843-1846). There is a possible genetic relationship between the selection for large-breasted birds and this condition. Management procedures that discourage excessive wing flapping would reduce the incidence (Jordan and Pattison. 1998. Poultry diseases. 398-399).

• Korean Journal of Poultry Science
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• v.49 no.2
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• pp.99-108
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• 2022

Avian leukosis virus (ALV) is a highly contagious retrovirus that causes tumors and has resulted in great economic loss worldwide owing to its high transmission rate. Various ALV viral subgroups exist, with infections occurring via specific host receptors. The susceptibility or resistance of avian species to the ALV-A and K subgroups is determined by the host receptor, the tumor virus locus A (tva) gene, while that to ALV-B depends on another host receptor, the tumor virus locus B (tvb) gene. The resistance alleles of tva and tvb have primarily been identified in China, but none have beendetected in Korea. We analyzed the frequencies of tva and tvb genotypes in White Leghorn (WL), Korean Ogye (KO), and Korean native chicken (KNC) breeds, and assessed the resistance to ALV subgroups. In WL, both tva and tvb had various genotypes, including susceptibility and resistance alleles, whereas in KO, tva and tvb resistance alleles were dominant. In KNC, tva susceptibility and resistance alleles were mixed, whereas tvb resistance alleles were dominant. In addition, we showed that there were differences in the splicing pattern of tva transcripts and the expression level of tvb transcripts within breeds. Finally, we confirmed that ALV resistance depended on KO and KNC genotypes by in vitro infection of chicken embryonic fibroblasts with ALV. These results highlight that some KO and KNC individuals are naturally resistant to ALV subgroups A, B, and K, and will facilitate the preservation of economically superior traits through selective breeding.