Eggshell quality: a comparison between Fayoumi, Gimieizah and Brown Hy-Line strains for mechanical properties and ultrastructure of their eggshells

Abstract

This experiment was designed to study the relationship between mechanical properties and ultrastructure of three genetic groups (Fayoumi, Gimieizah and Brown Hy-Line strains). To assess eggshell mechanical parameters a total of 120 eggs from each strain was used. This study suggested predicting the mechanical properties and ultrastructure of eggshells when egg weight was equal for the three strains (39.8 g). There was a significant difference among strains for shell thickness, eggshell breaking strength and stiffness, with the Fayoumi eggshells recording the highest values compared with other strains. The palisade layer of Gimieizah and Brown Hy-Line eggshells was thinner than that of Fayoumi eggshells. There were significant correlations between palisade length and breaking strength (0.51), shell thickness (0.89) and stiffness (0.48); however, the length of the palisade layer was significantly negatively correlated with elasticity (–0.85). The Fayoumi (local Egyptian strain) showed higher resistance for eggshell breakage than the Hy-Line commercial strain due to their longer palisade layer noting that there were no significant differences in egg weight between the two. The length of the palisade layer plays an important role in eggshell strength, so it is of interest to include these parameters in selection programs aimed to improve eggshell strength. However, a negative correlation between length of palisade layer and elasticity prevented improvement of these two parameters.