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. 2023 Feb;102(2):102376.
doi: 10.1016/j.psj.2022.102376. Epub 2022 Dec 5.

Structural characteristics of speckled chicken eggshells and their effect on reproductive performance

Xue Cheng  1 , Ying Ma  1 , Xinghua Li  1 , Yuchen Liu  1 , Ruiqi Zhang  1 , Yalan Zhang  1 , Cuidie Fan  2 , Lujiang Qu  1 , Zhonghua Ning  3
Affiliations

Structural characteristics of speckled chicken eggshells and their effect on reproductive performance

Xue Cheng et al. Poult Sci. 2023 Feb.

Abstract

Speckles are common on the brown eggshells of chicken eggs, especially for aged hens. They are important as they affect the consumer preference and economic value of eggs. The cause of speckles in eggshells is still unclear. In this study, we verified the difference of eggshell quality between speckled eggs and normal eggs. Structural characteristics of speckled eggshells were investigated using a scanning electron microscope. Results showed no significant difference in the eggshell quality between normal eggs and speckled eggs, except for a lower eggshell color-L value in the latter. More materials deposited between vertical crystal layer and cuticle layer in the speckled shell region, leading to the thicker eggshell than adjacent normal area. The relative content of protoporphyrin IX was significantly higher in the speckled area than in the adjacent normal area of the eggshells. In addition, there was no significant differences in productive and reproductive performance between hens that laid normal eggs or speckled eggs, except for a lower hatchability of the speckled eggs. In conclusion, we infer that the uneven distribution of eggshell pigment protoporphyrin IX leads to the formation of speckled eggs. This is the first study to establish the characteristics and causes of speckled eggshells. Moreover, this study provides novel insights into external egg quality and a foundation for the in-depth study of speckled eggshells.

Keywords: chicken egg; eggshell quality; protoporphyrin IX pigment; speckle.

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Figures

Figure 1
Figure 1
Scanning electron microscopy (SEM) images. (A) Longitudinal section of the speckled eggshell region. (B) Longitudinal section of the background color region. (C) Cuticle layer of speckled region. (D) Cuticle layer of background color region. Red line: eggshell thickness; blue line: effective eggshell thickness; yellow line: cuticle layer thickness. Scale bars are: (A) and (B) 50 µm, (C), and (D) 5 µm.
Figure 2
Figure 2
Protoporphyrin IX content between the speckled and adjacent normal region. ⁎⁎P-value < 0.01.
See this image and copyright information in PMC

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