Kurdistan Region Government –Iraq Ministry of High Education and Scientific Research

Salahhaden UniversityAgriculture CollegeAnimal Resource Department

 

The Study of Eggshell Color

P r e p a r e d b y : m u h s i n a l i a h m e d

M s c i n b i o t e c h n o l o g y

A n i m a l r e s o u r c e s d e p a r t m e n t

M u h s i n . A h m e d @ s u . e d u . k r d

M o b i l e n o : 0 0 9 6 4 7 5 0 4 9 3 5 0 9 9

Introduction Bird eggs show an enormous diversity of colors, from white, brown and blue to

green.

The egg color is considered as a: protection from harmful solar radiation reinforcement of eggshell structure and thermal protection of developing

embryos. Eggshell pigment has also been shown to have antimicrobial properties,

particularly against gram-positive bacteria

Figure 1. Chicken eggs show the variety of colors.

Figure 2. Structure of protoporphyrin-IX and biliverdin-IX. (a) Protoporphyrin-IX

(b) Biliverdin-IX

kennedy and Vevers (1976) found that eggshell pigments consist of protoporphyrin-IX, biliverdin-IX, secreted onto the surface of the eggshell by the shell gland (Wang et al., 2007).

Among the eggshell pigments, biliverdin is responsible for the blue-green eggshell color, whereas protoporphyrin is associated with the reddish-brown color. (Figure 2).

The metabolism process of biliverdin in bile, heme oxygenase-1 (HO-1) is the rate-limiting enzyme in the catabolism of heme to biliverdin, Fe2+, and CO (Maines, 1988).protoporphyrin IX (PpIX) which was synthesized in the shell gland.

Figure 3. The process of heme biosynthesis and catabolism (linked by solid arrow) and the predicted process of transformation from heme to eggshell protoporphyrin and eggshell biliverdin (linked by dashed arrow) (Wang et al., 2007)

Review Literature

In a study by Wang et al. (2009), on the 45 Dongxiang brown-shelled chickens, and

50 hens Dongxiang blue shelled chickens.

The correlation coefficient between the biliverdin and protoporphyrin content in the eggshells of the Dongxiang blue-shelled chickens is 0.74 (P < 0.01)

Table 1. t-test for the statistical difference of Qp, Qb, or QT between Dongxiang blue- shelled chickens and Dongxiang brown-shelled chickens1

1Qp = the quantity of protoporphyrin in 1 g of eggshell (mol/g); Qb = the quantity of biliverdin in 1 g of eggshell (mol/g); QT = the total quantity of pigments in 1 g of eggshell (mol/g), is equal to Qp plus Qb. E = the power with the base of 10. Wang et al. (2009) 

Review Literature

In a study by Zhao et al. (2009) on tissues of serum, bile, excreta, shell gland and eggshells of 78 hens which laid blue-shelled eggs and light brown

Table 2. Comparison of biliverdin content in different tissues1n = 10.

2UV = ultraviolet.3From eggs collected in shell gland.4From eggs laid.

Review Literature

In a study by Guangqi et al. (2013) on Rhode Island red pureline for quantify PpIX content in the eggshell, Excreta, bile, blood, liver, and shell gland in both darker shell group and lighter shell group of hens.

Table 3 . Protoporphyrin IX (PpIX) content in different tissues of hens in the darker shell group and lighter shell group

Table 4: Genotypes and phenotypes of eggshell color

No.

phenotypes Genotypes Pigment

1 Dark brown (1o,o/Br, Br) Only protoporphyrin High 2 Light brown (o, o/ Br, br) Only protoporphyrin Low 3 White (o,o/ br, br) Absent any pigments 4 Light blue (2O,o/ br,br) Only Biliverdin Low 5 Dark blue (O,O/ 3br, br) Only Biliverdin High 6 Light green (O,O/ 4Br, br)

(O,o/ Br, br)Biliverdin High Protoporphyrin Low

7 Dark green (O, O/ Br, Br) Biliverdin High Protoporphyrin High

1- o / recessive allele responsible to absent of blue color2- O/ dominant allele responsible to present of blue color3- br/ recessive allele responsible to absent of brown color 4- Br/ dominant allele responsible to present of brown color

Conclusion

1- The difference between the brown and blue egg shell are protoporphyrin-IX and biliverdin pigments respectively which are both derived from hem blood 2- The egg shell color is one of quality marker in the customer therefore the breeders during of egg laying chicken improvement should be paying attention to genetic of egg shell color.

Refrences Li, Guangqi ( 2013). Comparison of protoporphyrin IX content and related gene expression in the tissues of chickens laying brown-shelled eggs. Journal of Poultry science Association. 92:3120-3124 

Zhao, R., G. Y. Xu, Z. Z. Liu, X. Y. Li, and N. Yang. (2006) . A study on eggshell pigmentation: Biliverdin in blue-shelled chickens. jounal of Poult. Sci. 85:546-549. 

Wang, X. T., X. M. Deng, C. J. Zhao, J. Y. Li, G. Y. Xu, L. S. Lian, and C. X. Wu. (2009). comparison of the total amount of eggshell pigments in Dongxiang brown-shelled eggs and Dongxiang blue-shelled eggs. Journal of Poultry Sci. 88:1735–1739. 

Wang, X. T., X. M. Deng, C. J. Zhao, J. Y. Li, G. Y. Xu, L. S. Lian, and C. X. Wu. ( 2007). Study of the deposition process of eggshell pigments using an improved dissolution method. Journal of Poultry Science. 86:2236–2238.

Liu, H. C., M. C. Hsiao, Y. H. Hu, S. R. Lee, and W. T. K. Cheng. (2010). Eggshell pigmentation study in blue-shelled and white-shelled ducks. Asian-Australas. Journal of Animal Science . 23:162-168.