Differences in internal egg quality characteristics between white and brown shell eggs

This study was conducted to reveal the differences among the internal quality characteristics of brown and white shell table eggs and to examine the relationship between quality characteristics. A total of 235 eggs from brown and white laying hens (Nick-chick; 95 wk of age) were used in this study. Internal egg quality characteristics including egg weight, albumen height, Haugh Unit, yolk height, yolk index, albumen pH, yolk pH, yolk color were determined. The Haugh unit (P<0.001), Albumen height (P<0.001), yolk L* (P<0.001) and yolk b* (P<0.05) values of white shell eggs were higher than that of brown shell eggs. On the contrary, the yolk a*(P<0.01), yolk height (P<0.01) and yolk index (P<0.01) values of white shell eggs were lower than that of brown shell eggs. There were no significant differences were found between white and brown shell eggs for egg weight, albumen and yolk pH values. Significant (P<0.001) positive correlations were found between albumen height and Haugh unit (r= 0.97), yolk height and yolk index (r=0.91), albumen pH and yolk pH (r=0.95) in internal egg quality of white shell eggs. Similarly, there were significant (P<0.001) positive correlations between albumen height and Haugh unit (r= 0.97), yolk height and yolk index (r=0.88), egg weight and albumen height (r=0.39), albumen height and yolk height (r=0.35), Haugh unit and yolk index (r=0.36) in internal egg quality of brown shell eggs. Significant (P<0.001) negative correlation were found between yolk L* and yolk a* (r=-0.41) in white shell eggs, and yolk L* and yolk a* (r=-0.56) in brown shell eggs. No significant relationships were observed among others internal egg quality criteria.