Smaller hens's eggs and yolks are composed of smaller yolk spheres, and vice-versa for larger yolks. We examined whether the size of the yolk spheres was related to the size of eggs and yolks in eggs from different birds. The cross-sectional area of the yolk spheres in the intermediate layer of steamed yolks was measured by the image-processing technique.
The weights of the eggs and yolks from different birds were greatest in the ostrich (>duck>White-Leghorn >Nagoya>guinea fowl>quail). The weight of an ostrich egg was about 25 times greater than that of hen eggs,, and about 120 times greater than that of quail eggs. The cross-sectional area of yolk spheres was greatest in the White-Leghorn (>ostrich>duck>Nagoya>quail>guinea fowl). There was no significant correlation between the cross-sectional area of yolk spheres and the yolk weight in eggs from different birds (r=0.12).
The kinds of bird egg cannot be identified by the different cross-sectional areas of the yolk spheres.
