Analysis of relationship of egg weight and specific gravity with incubation mortality in chickens

Effect of egg weight (EW), specific gravity (SG) and shape index (SI), on components of incubation mortality was examined based on 2910 eggs of a long-term selected strain of White Leghorn. EG and SG of the dams exhibited negative skewness and positive kurtosis. Within the entire range of the egg weight of the dams studied (49.1 to 67.0g), an increase in egg weight resulted in increased total incubation mortality (b= 0.71±0.3%) that resulted from increased late and pipping mortality. The relationship between egg weight and embryonic mortality was curvilinear with the linear and quadratic terms explaining 23.0 and 25.2% of the variability, respectively. The relationship between SG and embryonic mortality was curvilinear where quadratic component accounted for 59% of the variation. Multiple regression analysis of embryonic mortality on EW, SG and SI showed that these variables explained 76.7% the variation, but the contribution of SI was non-significant. EW as the first variable in the model explained 60.9% of the variation while SG as the first variable explained 40.1% of the variation. The following regression equation was developed to describe the relation of total mortality with egg weight (EW) and specific gravity (SG) with R² = 74.4%

Y = 10.37 + 240 EW + 2.1 EW² + 74 SG + 0.11 SG²