Objective   The egg-laying of Chahua chickens was analyzed, and applicable prediction models evaluated.

  Methods   The indicators of egg-laying performance, including the age and body weight of chicken at start of egg-laying and the individual weight and number of eggs of 30- and 43-week-old chickens, were recorded for a Pearson correlation analysis. Various nonlinear models for curve fitting on egg production rate and cumulative egg production of 20- to 45-week-old chickens were compared.

  Results   The coefficients of variation on the initial egg-laying age and the egg weight of 30- and 43-week-old chickens were below 10%. But those on the body weight at start of egg-laying and the numbers of eggs laid at 30- and 43-week were higher than 10%. There were significant correlations among 10 characteristics of the egg-laying performance (P＜0.05). For instance, a significant inverse correlation was observed between the chicken body weight and age at first egg-laying, between the age at start of egg-laying and the egg number of 30- and 43-week-olds, and between the egg weight of 30-week-olds and the numbers of eggs laid by the 30- and 43-week-old chickens. Whereas significant positive correlations were found between the body weight of chickens at time of initial egg-laying and the egg weights of 30- and 43-week-olds and between that and the egg weight of 30-week-olds. Significant correlations were also shown between the egg weight of 30-week-old chickens and that of 43-week-olds, and between the number of eggs laid by the 30-week-olds and that by 43-week-olds. Among the tested models, Yang-Ning had the highest R² of 0.990 on curve fitting for the egg yield. For the cumulative egg yield, all 3 models yielded R² above 0.991 with Von Bertalanffy being the highest at 0.999.

  Conclusion   There appeared rooms for performance improvements on the body weight of the birds that started laying eggs and the weights of individual egg laid by the 30- and 43-week-old Chahua chickens, but less so on the starting age of egg-laying and the weights of egg of the 30- and 43-week-olds. Since the egg weight negatively correlated to the number of eggs laid by the chickens, in addition to the starting age of egg-laying, those factors would need be put into consideration in breeding selection. Yang-Ning model seemed adequate for the rate prediction and evaluation, while Von Bertalanffy for the cumulative egg production estimation on Chahua chickens.