Repeatability estimates of external and internal egg quality traits in Japanese quail

Abstract

Twenty-five (25) freshly laid Japanese quail (Cortunix japonica) eggs, randomly selected weekly for 7 weeks from the base population of 249 birds were used to estimate the repeatability of external and internal egg quality traits. External egg quality traits were Egg Weight (EWT), Egg Length (EL), Egg Width (EW), Shell Weight (SWT) and Shell Thickness (ST). Internal egg traits were Yolk Height (YH), Yolk Diameter (YD), Albumen Height (AH), Albumen Diameter (AD), Yolk Weight (YWT) and Albumen Weight (AWT). Variance components and Repeatability estimates were obtained using the one-way Analysis of Variance (ANOVA) with the Computer aided Software, Statistical Analysis System (SAS, version 8). High repeatability estimate (0.76) was observed for egg weight. Only egg weight would require a maximum of 7 records to characterize the inherent producing ability of each hen. Selection for improvement using egg weight will result in good performance and significant genetic gain. More records would be needed to achieve this for other external and internal egg quality traits. From this study Egg weight should therefore be adopted as the key determinant for repeatability estimations in Japanese quail.