• Korean Journal of Poultry Science
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• v.20 no.1
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• pp.1-9
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• 1993

This study carried out to build up new synthetic egg production lines which had sex-linked gene for feather color sexing and also superior combining ability for producing the best commercial chicks. The closed flock breeding method was utilized to improve the general performances in the first experiment and combining ability for heterosis was tested for new synthetic line in the second experimental year. In order to test for the egg production ability in cross breeds synthetic lines, the crossing of B$\times$4 B$\times$C, two imported strains and two domestic strains as controls were compared for the general performances. There was on difference in mortality, body weight to 56 weeks of age. Sexual maturity was delayed about 10 days by comparing with other reports, except 153 days of the Manina White, but no difference among mating systems in this experiment. The hen housed egg production in B$\times$A, B$\times$C was 186.3, 191.3 respectively and it was better than the other controls, except ISA imported lines. The hen-day egg production of B$\times$A, B$\times$C was better than other controls, with 75.7%, 76.8% respectively. In the average egg weight, the B$\times$C cross breed was highest with 64.5g. As the sex of hatching chicks was identified by difference of feather color, the genetic composition of synthetic lines must be homogenized. The feather color of female chicks was brown and that of male was silver (99%), In conclusion, the egg production ability of B$\times$A, B$\times$C cross breeds was superior to the imported and domestic lines. Therefore, it suggest that the synthetic lines with sex-linked gene might be utilized for improving egg production performances.