닭의 경제형질에 대한 유전력 및 유전상관에 관한 연구 = Studies on the Heritabilities and Genetic Correlations among Economic Traits in Domestic Fowl .

다국어 초록 (Multilingual Abstract)

The purpose of this study was to evaluate the value of initial egg weights as selection criterion of laying hens for improvement of egg production performance. Data here used came from records of 406 white leghorn hen progenies produced by hierachal mating of 44 sires and 201 dams at three different hatching stages, which were maintained at Livestock Experiment Station. The data were analysed by the method of variance component analysis to estimate heritabilities, maternal variance, on 5 economic traits and genetic, phenotypic and environmental correlations among them. The results obtained were as follows: 1. The heritability estimates were 0.549 for body weight at first egg, 0.500 for age at first egg, 0.160 for initial egg weight, 0.398 for matured egg weight and 0.429 for egg number to 500 days. 2. The fraction of the total variance which were due to the maternal effect was 0.175 for body weight at first egg, 0.204 for age at first egg, -0.058 for initial egg weight, 0.140 for matured egg weight and 0.095 for egg number to 500 days. 3. The genetic correlations of body weight at first egg with age at first egg, initial egg weight, matured egg weight and egg number to 500 days were -0.503. 0.300, -0.186 and -0.105, respectively. The genetic correlations of age at first egg with initial egg weight, matured egg weight and egg number to 500 days were 0.501, -0.238 and -1.969. The genetic correlations of initial egg weight with matured egg weight and egg number to 500 days were 0.493 and -0.537. There was 0.068 of genetic correlations between matured egg weight arid egg number to 500 days. On the basis of the results obtained in this study, it is recommented that for the effective improvement of egg weight, selection should be practiced for initial egg weight.