Functional Insights for Eggshell Matrix Proteins: From Proteins to Genes to Selection Tools

Cracked and damaged eggs result in a substantial economic loss to the egg industry.The calcified poultry eggshell provides protection to the egg contents and embryo against physical damage and contamination by microorganisms. This complex bioceramic structure also regulates the exchange of metabolic gases and water, and provides calcium to the developing embryo. Changes in eggshell properties are directly related to increasing risk of egg contamination and food-borne disease for the consumer. During mineralization of the avian eggshell, there is a sequential and orderly deposition of both matrix and mineral phases. The majority of constituents of the chicken eggshell have been identified, in particular the relatively eggshell - specific Ovocalyxins and Ovocleidins. An organized review of eggshell matrix proteins will be presented with focus on the results of recent structural, transcriptomic and proteomic analyses of the eggshell, in order to draw attention to the impact of this data on current understanding of eggshell mineralization and ultrastructure / microstructure that contribute to shell strength. Moreover, there is increasing evidence that genes involved in eggshell formation and mineralization are functional candidates for marker assisted selection to improve egg and eggshell quality.