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정선부 충남대학교 대학원 1971 논문집 Vol.3 No.-
The purpose of this study was to investigate the methods of early selection for effective improvement of various economic traits in laying hens. The data used in these studies were the records of 1058 New Hemp-shire hens which were raised at Tajon Branch Station of National Aminal Breeding Station for 5 years from 1965 to 1969. Heritabilities and maternal variances were estimated by the method of variance component analysis for 15 economic traits. Phenotypic, genetic and environmental correlations among these traits were also estimated. The results obtained are asfollows. 1. The heritabilities estimated were 0.31 for body weight at 8 weeks, 0.46 for body weight at age at first egg, 0.34 for body weight at 300 days, 0.39 for body weight at 500 days, 0.31 for intensity of egg production, 0.44 for winter pause, 0.36 for egg weight, 0.55 for age at first egg, 0.40 for egg production to 200 days, 0.50 for egg production to 250 days, 0.60 for egg production to 300 days, 0.62 for egg production to 350 days, 0.57 for egg production to 400 days, 0.56 for egg production to 450 days and 0.46 for egg production to 500 days. 2. The fraction of the total variance which due to the maternal effect was 0.18 for body weight at 8 weeks, 0.108 for body weight at age at first egg, 0.08 for body weight at 300 badys, 0.28 for winter pause, 0.11 for age at first egg, 0.18 for egg weight and 0.08 for number of egg production to 200 days of age. 3. The genetic correlations of body weight at 8 weeks of age with body weights at different ages, number of egg production, egg weight and winter pause were positive, but correlations of body weight at 8 weeks with age at first egg and intensity of egg production were nagative. There were positive genetic correlations for body weight at age at first egg with body weight at each stage, egg weight and age at first egg. In the genetic correlations between body weight at first egg and number of egg production, negati e correlations were found in early stages of egg production but in late stages, the correlations turned to positive. There were positive genetic correlations for body weight at 300 days with body weight at 500 days, egg weight and age at first egg, but the body weight at 300 days was negatively correlated with number of egg production in all stages. Genetic correlations for body weight at 500 days with intensity of egg production, egg weight and number of egg production at each stage except for egg production to 500 days were positive. The genetic correlations of egg production to 500 days with egg production to 200 days, to 250 days, to 300 days, to 350 days, to 400 days, and to 450 days were 0.44, 0.66, 0.55, 0.69, 0.87 '0.97 respectively. 4. On the basis of the results obtained in this study, it is recommended that for the effective improvement of egg production, selection should be practiced for bodyweight at 8 weeks of age at first, selection at next stage be practiced for age at first egg, and then for egg production to 300 days of age.
정선부 대한양계협회 1983 월간 양계 Vol.15 No.1
닭의 개량이 선진국에서만 가능한 것이 아니고 우리도 자금을 투입해 체계적인 육종사업을 실시한다면 발전의 무한한 가능성을 지니고 있다.