• Korean Journal of Poultry Science
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• v.6 no.1
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• pp.31-37
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• 1979

The propose of the present study was to evaluate the relative economic importance of the major Production traits in laying hens. Based on the results of this study, it was showed that feed requirement, average egg weight and hen-housed e99 Production influenced greatly on the income over feed and chick cost.

• Korean Journal of Poultry Science
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• v.41 no.3
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• pp.191-196
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• 2014

The identification and utilization of potential candidate genes with significant effects on economically important traits have become increasingly important in poultry breeding programs. The ovocalyxin-32 (OCX-32) gene is located chromosome 9 in chicken, plays an important role in eggshell formation. This study was performed to assess the association between single nucleotide polymorphisms (SNPs) of OCX-32 gene and egg production traits in the Korean native chicken. Four Korean native chicken population (n = 181; including 46 females of Ogol, 46 females of white, 43 females of gray and 46 females of black) were used to analyze two SNPs (c.494A>C and c.267T>G) in the OCX-32 gene by PCR-RFLP (Polymerase Chain Reaction-Restricted Fragment Length Polymorphism). We measured egg production traits of age at first egg, first egg weight, egg production ratio and egg weight. The SNP c.494A>C was significantly associated with egg production ratio in Korean Ogol chickens (p<0.001) and egg weight in Korean white chickens (p<0.05). SNP c.267T>C was significantly associated with egg weight in Korean Ogol chickens (p<0.05). But there was no significant association in Korean gray and black chickens. Results suggest the possibility of using molecular markers in OCX-32 gene as a tool for performance and egg production traits in Korean native chicken breeding program.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2002.11a
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• pp.140-142
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• 2002

This study was conducted to obtain some genetic information for developing superior Korean native chickens. Heterosis and combining ability effects were estimated with 1,080 progenies of full diallel crosses of 3 strains in Korean Native Chicken. The traits of egg productivity were Investigated, and heterosis effect, general combining ability, specific combining ability and reciprocal effect were analyzed model I of the Griffing's method 1. The general performance were 147.0 days in age at first egg laying, 71.8 eggs in egg numbers to 270 days, 50.1g in egg weight at 270 days, 75.6 in egg shape index, 356$\mu\textrm{m}$ in egg shell thickness, and 4.27kg/$\textrm{cm}^2$ in egg shell strength, respectively. According to result, heterosis effect revealed comparatively high in age at first egg laying, egg numbers, egg weight, and egg shell strength. The effects estimated highly in general combining ability for age at first egg laying, egg numbers, egg weight, egg shape Index and egg shell thickness, and in specific combining ability were egg numbers, egg weight and egg shell thickness, and in reciprocal effects for egg numbers, egg shape index, and egg shell thickness. This result could be used for developing Korean native chicken.

• Korean Journal of Poultry Science
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• v.16 no.2
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• pp.61-71
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• 1989

The purposes of this study were to investigate the genetic variations by backcrossing in commercial chickens. Backcrossing was carried out successively back to parent stock (P.S). Heritabilities and genetic correlation coefficients were estimated to verify the genetic variations. The data obtained from a breeding programme with commercial chickens (I strain) were collected from 1955 to 1987 at Poultry Breeding Farm, Seoul National University. Data came from a total of 1230 female offspring. The results obtained are summarized as follows： 1. The general performance ($Mean\pmStandard deviation$) of each trait was $663.94\pm87.11$g for 8 weeks body weight, $1579.1\pm155.43$g for 20 weeks body weight, $2124.1\pm215.3$g for 40 weeks body weight, $2269.1\pm242.94$g for 60 weeks body weight, $168.43\pm12.94$ day for a9e at sexual maturity (SM), $214.52\pm29.82$ eggs , for total egg number to 60 weeks of age (TEN), $61.45\pm3.48$ g for average weight (AEW), $13180.7\pm1823.22$ g for total egg mass to 60 weeks of age(TEM). All traits, except 10 weeks body weight and AEW, were significant for the degrees of backcross (p＜0.01). 2. The pooled estimates of heritabilities derived from the sire, dam and combined variance components were 0.47~0.52 for age at sexual maturity (SM), 0.07~0.37 for total egg number (TEN), 0.40~0.54 for average egg weight (AEW), 0.18~0.27 for total egg mass (TEM). High heritability estimates were found for SM and AEW. TEN and TEM were estimated to be a lowly heritable traits. Heritability estimates from dam components were higher than those from sire components. These differences might be due to non-additive genetic effect and maternal effect. 3. The estimates of heritabilities and standard errors derived from combined variance components for different degrees of backcross were $0.47\pm0.11$ (BCO), $0.42\pm0.16$ (BC1), $0.51\pm0.29$ (BC2) for TEN, $0.59\pm0.20$ (BCO), $0.43\pm0.17$ (BC1), $0.35\pm0.18$ (BC2) for AEW, $0.28\pm0.12$(BC0), $0.20\pm0.11$(BC1), $0.18\pm0.14$ (BC2) for TEM. Heritability estimates for AEW and TEM were decreased by backcrossing while those for SM and TEN remained constant. Since backcrossing contributes to increased homozygosity, the genetic variation of the traits (AEW and TEM) decreased . 4. The pooled estimates of genetic correlation coefficients were -0.55 between SM and TEN, 0.20 between SM and AEW, -0.29 between TEN and AEW, 0.82 between TEM and TEN, 0.31 between TEM and AEW, -0.42 between TEM and SM. The genetic correlation between TEM and TEN was higher than that between TEM and AEW, and it was suggested that egg mass was strongly affected by egg number. Also, age at sexual maturity(SM) contributes to egg mass(TEM). 5. When backcrossing was carried out successively, the genetic correlation between TEM and TEN increased (BC0：0.79, BC1：0.82, BC2：0.91) but those between TEM and SM decreased (BC0：-0.54, BC1：-0.36, BC2：-0.09) with successive backcrosses.

• 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.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 POULTRY JOURNAL
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• v.41 no.8
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• pp.134-135
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• 2009

• KOREAN POULTRY JOURNAL
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• v.10 no.11 s.109
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• pp.189-194
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• 1978

• KOREAN POULTRY JOURNAL
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• v.11 no.8 s.118
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• pp.131-136
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• 1979

• Proceedings of the Korea Society of Poultry Science Conference
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• 2004.11a
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• pp.97-98
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• 2004

The observed means and standard divisions of the major laying traits per generation in korean native chickens were as follow. The age at first egg, the egg weight at the first egg, the weight at 270days and the egg production to 270days were 147.1$\pm$1.9 days. 32.3$\pm$0.9 g, 49.4$\pm$0.7 g and 76.2$\pm$1.7 eggs. The regression coefficients were -0.75$\pm$0.01 days, 0.33$\pm$0.08 g, 0.19$\pm$0.05 g and 0.47$\pm$0.3 eggs respectively.