Abstract: [Objective] To investigate the growth and development rules of chicks of Hy-Line Brown laying hens and Jingfen No.2 laying hens under the identical rearing condition, and to assess their first egg qualities. [Method] A total of 1 000 chicks of 1-day-old Hy-Line Brown laying hens （n=500） and 1-day-old Jingfen No.2 laying hens （n=500） were selected and reared under the same condition. Sixty individuals of each laying hen breed were randomly chosen every week to measure their body weights until the 13 weeks of age （the end of the experiment）. Three curve models, including Logistic, Gompertz and Von Bertalanffy, were used to fit the growth and development of the chicks of both breeds. About 30 days after moving into coops, the experimental hens were monitored for starting of egg-laying, and the first eggs of both breeds were collected to determine and compare the quality indexes. [Result] The chicks of both breeds got the fastest growth rate during the 4-5 weeks of age. The used curve models as Logistic, Gompertz and Von Bertalanffy were all well fitting for the body mass data of both breeds, among which, Gompertz had the best performance due to its higher degree of fitting and better suitability. In the comparison of first egg qualities, all parameters of Hy-Line Brown laying hens were significantly higher （P<0.05） than those of Jingfen No.2 laying hens except for egg width and egg shape index. [Conclusion] These findings may provide referential data for the development, utilization and breed improvement of Hy-Line Brown laying hens and Jingfen No.2 laying hens.

Key words: Hy-Line Brown laying hens, Jingfen No.2 laying hens, growth and development, first egg, egg qualities