Characterization of protein composition of guinea fowl (Numida meleagris) egg white

The guinea fowl is a poultry species whose breeding represents only a small portion of the poultry sector because of its low laying rate compared to the hen. The structure and interior of eggs show significant species differences, which may also contribute to differences in their biochemical composition. This may be particularly evident in the protein composition of the egg, which determines the specific profile of biological activity, including resistance to biotic and abiotic stresses. A detailed understanding of the egg proteome in various avian species, including guinea fowl, has both biological and technological relevance. Egg white proteins play essential roles in embryo protection, antimicrobial defence and determining the functional and nutritional properties of eggs as a food product. Therefore, identifying species-specific differences is important not only for comparative avian biology, but also for the development of novel applications in food processing, biotechnology, and breeding strategies aimed at improving the quality and storage stability of eggs. The vast majority of research has focused on determining the protein profiles of chicken egg components. Therefore, the present study focuses on the protein composition of the egg protein of another poultry species: the guinea fowl. Using two-dimensional electrophoresis (2-DE) combined with mass spectrometry (MALDI-TOF MS), we analyzed the protein composition of guinea fowl egg whites. We identified six key proteins, namely ovalbumin (OVAL), ovalbumin-related proteins X and Y (OVALX and OVALY), ovotransferrin (LTF), lysozyme C (LYSC) and GDP-mannose 4,6-dehydratase (GMDS). These proteins have primarily immune, reserve and embryonic development functions. They have previously been found in studies on eggs of other avian species. However, the presence of GMDS in avian eggs has not been confirmed before, except by one study on the protein profile of guinea fowl eggshells.