Fig. 1
From: Inheritance of the duration of fertility in chickens and its correlation with laying performance
Duration of fertility (DF) and the five traits to measure it. a Hen-day laying rate and hatchability at 35 and 60 weeks of age. b Histogram of the number of eggs incubated for each hen at 35 and 60 weeks of age. c Examples of five traits used to determine DF; and (d) Histogram of the five DF traits at 35 and 60 weeks of age. The red dashed line is the mean value of the corresponding trait at a given age. Data are expressed as the mean ± SD. The estimates may not represent the true statistics for these DF variables since the eggs were only collected during 15 days. The P value indicates the significance of the difference between the same variable measured at two ages