The document discusses eggshell pigmentation in chickens. It finds that biliverdin is responsible for blue-green shells while protoporphyrin causes reddish-brown shells. Studies showed a correlation between biliverdin and protoporphyrin levels in blue-shelled chickens. Tissue analysis found higher pigment levels in shell glands and eggshells of darker-shelled chickens. Genetic factors influence the presence or absence of blue and brown pigments, determining shell color.

1. Kurdistan Region Government –Iraq
Ministry of High Education and Scientific Research
Salahhaden University
Agriculture College
Animal Resource Department
P re p a re 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 re s o u rc 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

2. 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.

3. 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).

4. 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)

5. 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)

6. 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)

7. 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

8. Table 2. Comparison of biliverdin content in
different tissues
1n = 10.
2UV = ultraviolet.
3From eggs collected in shell gland.
4From eggs laid.

9. 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.

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

11. 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 color
2- O/ dominant allele responsible to present of blue color
3- br/ recessive allele responsible to absent of brown color
4- Br/ dominant allele responsible to present of brown color

12. 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.

13. 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.