The Effect of Mechanical Disturbance of the Egg Cuticle on Shell Mottling

Shell mottling as described by Holst et al. (1932) has been a troublesome defect to market egg producers using caged layers. Many commercial egg handlers and processors instruct their personnel working in the candling booth, to remove and downgrade many of these mottled eggs because the light-colored, translucent marks often appear similar to blind (nearly invisible) cracks in the shell. A blind crack permits water from the egg contents to blot into the surrounding shell area producing a translucent area. This suggests that shell mottling as described by Holst et al. (1932) represents portions of the shell that have absorbed water from the egg contents. They showed that no relationship existed between egg shell mottling and shell thickness. Baker and Curtis (1957) concluded there was no correlation between specific gravity and shell mottling or shell thickness and shell mottling. Brown and white-shelled eggs observed by the author at commercial egg . . .