Abstract
The objective of this study was to evaluate the internal and external quality of eggs classified as eggs with normal eggshell and eggs with vitreous eggshell, produced by hens at three different ages. Forty-five eggs of each eggshell type, normal and vitreous, were sampled at the ages of 30, 50, and 70 weeks. The weight of the egg, in both types of eggshell, increased with the advancing age of the hen. Higher concentration of calcium was found in eggs with normal eggshells comparing to eggs with vitreous eggshells. The eggshell type did not affect phosphorus percentage. The mineral deposition of the eggshell was constant. The skin thickness increased irrespective of the shell along the reproductive life of the chicken and decreased when the bird became older. The percentage of albumen increased, while the percentage of albumen protein and pH decreased throughout the ages. Percentage of egg yolk, humidity, and pH decreased with increase of age of the laying hen, whereas crude protein and lipid increased. Eggs with vitreous eggshell showed eggshell with lower quality compared to those with normal eggshell, without, however, compromising the internal quality of albumen and yolk.
Keywords:
egg quality; eggshell types; physical analysis