Estimation of Heritability and Permanent Environmental Effects of Egg Traits in the Blue-Breasted Quail (Synoicus chinensis)

The blue-breasted quail (Synoicus chinensis), owing to its small body size and rapid reproductive cycle, represents a suitable material for the genetic analysis of egg traits. Egg weight, length, width, and other traits derived from these measurements are of critical importance for both embryonic development and the success of genetic improvement programs. This study aimed to estimate heritability and permanent environmental effects for measured and derived egg traits in blue-breasted quail. A total of 6,602 individual records of egg weight, length, and width were collected from 104 female quails between 49 and 402 days of age. Derived traits included shape index, volume, surface area, density, and surface-volume index. Additive genetic and permanent environmental variance components related to egg traits were estimated, and the effects of generation, incubation group, year, month, and age were taken into account in the analyses. Heritability estimates (h²) were high for the surface–volume index (0.54) and density (0.47), moderate for weight (0.25), width (0.26), and volume (0.24), and low for length (0.15) and lowest for shape index (0.08). The variance ratio of permanent environmental effects (pe²) to total phenotypic variance varied between 0.23 and 0.43, reaching its maximum for the surface–volume index (0.43) and density (0.38). Partial correlation analysis among the various parameters revealed strong positive relationships between egg weight and length (r=0.75), width (r=0.85), volume (r=0.93), and surface area (r=0.93), whereas a strong negative relationship between the shape index and surface–volume index was identified (r = −0.99). These findings have important implications for expected selection efficiency and, when validated in larger datasets, may substantially enhance the reliability and practical applicability of breeding programs in the species.