• Korean Journal of Poultry Science
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• v.24 no.1
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• pp.29-37
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• 1997

An experiment was conducted for 20 days( from July 21 to August 10, 1996) to investigate the differences in thickness of eggshell and eggshell membrane in Korean native chicken. All the eggs were purchased from a farm located in Chinju area. All eggs were categorized into Treatment I (34.89~51.39 g), H (53.32~60.70 g), and III (34.89~60.70 g) according to their weights. Eleven items were measured in all three treatments, i.e., egg weight, egg length, egg width, breaking strength, eggshell thickness of large end(STLE), eggshell membrane thickness of large end(SMTL), eggshell thickness of small end (STSE), eggshell membrane thickness of small end(SMTS), eggshell thickness of middle part(STMP), and eggshell membrane thickness of middle part(SMTM). Correlation coefficients between egg weight and eggshell weight, among eggshell thickness of large end, small end and middle end and eggshell weight were significant (P<0.01). Correlation coefficients between egg weight and large eggshell membrane were nega-tively significant(P<0.01). Breaking strengths were higher in Treatment I than in Treatment H. Correlation coefficients among thickness of eggshell and eggshell membrane at each point at 3 parts of large end, small end and middle end were not significant.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.2
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• pp.290-296
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• 2003

Tsaiya ducks and Leghorn hens are the two major laying birds raised in Taiwan. They are all excellent egg layers. Tsaiya ducks are small in body size (1.3 kg) with bigger egg weight (65 g) and stronger eggshell breaking strength than eggs from hens. The eggshell consists mainly of calcium carbonate, hence calcium plays an important role in the eggshell formation. Magnesium is also present in eggshell in small amounts, which may have effect on maintaining eggshell quality. In comparison studies, it was shown that the duck eggshells contained higher calcium and lower magnesium content than chicken eggshells. The eggshell magnesium content was not affected by the dietary magnesium levels (690-2380 ppm) in ducks, but in hens, it increased linearly with dietary magnesium levels. The palisade layer ($5000{\times}$) of the eggshell was found to have a compact form for ducks while there are many hallow vesicles in chicken eggshells. The eggshell magnesium deposition model is different for ducks and hens with ducks having a one-peak and hens having a two-peak model. The calcium deposition model is similar for both birds. Both the carbonic anhydrase specific activity and total activity in the shell gland mucosa of ducks are higher than those in hens. Ducks retain higher magnesium and lower calcium in the shell gland mucosa and secret less magnesium and more calcium into the shell gland lumen for eggshell deposition. The ATPase specific activity is maintained fairly constant during the eggshell forming stage, indicating continuous calcium transport into the shell gland lumen for eggshell formation. The magnesium content in duck eggshells is much lower than that in hens indicating that the magnesium content in the eggshell may have an effect on eggshell quality.

• Animal Bioscience
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• v.34 no.5
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• pp.811-823
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• 2021

Objective: Eggshell color is an important indicator of egg quality for consumers, especially for brown eggs. Various factors related to laying hens and their environment affect brown eggshell coloration. However, there have been no studies investigating hepatic functions of laying hens with variable intensity of brown eggshell color. Therefore, this study was aimed to identify potential factors affecting brown eggshell coloration in aged laying hens at the hepatic transcriptomic level. Methods: Five hundred 92-wk-old Hy-line Brown laying hens were screened to select laying hens with different intensity of brown eggshell color based on eggshell color fans. Based on eggshell color scores, hens with dark brown eggshells (DBE; eggshell color fan score = 14.8) and hens with light brown eggshells (LBE; eggshell color fan score = 9.7) were finally selected for the liver sampling. We performed RNA-seq analysis using the liver samples through the paired-end sequencing libraries. Differentially expressed genes (DEGs) profiling was carried out to identify their biological meaning by bioinformatics. Results: A total of 290 DEGs were identified with 196 being up-regulated and 94 being down-regulated in DBE groups as compared to LBE groups. The Kyoto encyclopedia of genes and genomes (KEGG) analysis revealed that these DEGs belong to several biological pathways including herpes simplex infection (toll-like receptor 3 [TLR3], cyclin-dependent kinase 1, etc.) and influenza A (TLR3, radical S-adenosyl methionine domain containing 2, myxovirus [influenza virus] resistance 1, etc.). Genes related to stress response (ceremide kinase like) and nutrient metabolism (phosphoenolpyruvate carboxy-kinase 1, methylmalonic aciduria [cobalamin deficiency] cblB type, glycine receptor alpha 2, solute carrier family 7 member 11, etc.) were also identified to be differentially expressed. Conclusion: The current results provide new insights regarding hepatic molecular functions related to different intensity of brown eggshell color in aged laying hens. These insights will contribute to future studies aiming to optimize brown eggshell coloration in aged laying hens.

• Journal of Powder Materials
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• v.11 no.5
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• pp.391-398
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• 2004

Calcium phosphate powders were successfully synthesized by using re-cycled eggshell and phosphoric acid. The crystallization behavior and powder morphologies of the synthesized powders were dependent on the starting condition of the eggshell, the mixing ratio and method of the eggshell and phosphoric acid, and calcination temperature. In general, $\beta$-tricalcium phosphate was stably synthesized at about $900^{\circ}C$ for 1h at each proper mixing ratio. And, the synthesized powders showed the similar microstructures to the morphology of original eggshell with uniform particle sizes. In this study, the calcium phosphate powders were synthesized with eggshell in various processing method. And their unique microstructures obtained from the eggshell were also. observed. The crystalline developments and microstructures of the synthesized powders were examined by X-ray diffractometer and scanning electron microscopy.

• Journal of Animal Environmental Science
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• v.14 no.1
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• pp.47-52
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• 2008

Broken eggs not only cause the economic loss in the egg producing industry, but also may not be good for the consumer's health. In order to identify the causes of eggshell breakage in laying hen houses, analyses on the status of eggshell breakage in the step of egg conveyer system of the laying hen house were conducted. The survey of eggshell breakage rate was implemented by four different stages egg conveying system. In the results, the breakage rate showed 4.7% in the egg collection belt, 2.5% in the egg elevator, 1.7% in the egg grading system and 0.9% in the egg conveyor belt. In particular, to Hy-line Brown variety, as the hens' raising week old increased, the breakage rate of eggshell increased while the strength of eggshell decreased. In the regression analysis between the breakage rate of eggshell and the strength of eggshell, the coefficient of determination ($R^2$) by the test of significance was computed as 0.7, therefore the changes of the strength of eggshell affects the breakage rate of eggshell. However, between the strength of eggshell and thickness of egg shell, and between the strength of eggshell and strain of eggshell, there was no significant difference detected in the regression analysis.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2004.11a
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• pp.53-68
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• 2004

Eggshell quality is one of the most important factors that influence hatchability. The porosity and overall quality of eggshell have a very significant effect on exchange of vital gas (carbon dioxide and oxygen) between the developing embryo and the air during incubation. Thin-shelled eggs showed the greater weight loss than do thick-shelled eggs. causing the chick to have difficulty in hatching. Thin-shelled eggs also have a much greater chance of being cracked during handling. On the other hand. thick-shelled eggs showed the higher hatchability as a result of greater fertility and lower intermediate and late embryonic mortalities. Even a small percentage improvement in the eggshell quality could result in significant saving to the breeder industry in an increasingly competitive environment. Many factors including nutrition. management practices, environmental conditions and breeding are known to be related to eggshell quality. In this review brief accounts of each factor associated with eggshell quality and hatchability were provided. We conducted three experiments to investigate the effects of dietary Ca. vitamin D3 metabolite and some bioactive materials on eggshell quality and hatching egg production. The results of our studies showed that relatively high levels of dietary Ca in combination with 25-hydroxycholecalciferol had beneficial effects on improving eggshell quality and reproductive performances in aged egg-type breeder hens. It was also suggested that the proper use of some feed additives such as isoflavon and chitosan might provide means of improving eggshell quality and reproductive performances in aged egg-type breeder hens.

• Journal of Environmental Science International
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• v.26 no.7
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• pp.869-874
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• 2017

This study was conducted to investigate the effects of dietary supplementation of various types of fermented red ginseng marc with red koji to laying hens on eggshell and egg yolk quality characteristics. A total of 240 Hy-line Brown laying hens (40 wk of age) were randomly allotted to 24 pens (6 replicates per treatment and 10 laying hens per replicate). Experimental diets consisted of 4 treatments containing basal diet (control), 1% fermented red ginseng marc powder with red koji, 1% fermented red ginseng marc pelleted with red koji and 1% fermented red ginseng marc coated with red koji. During the 8-wk feeding trial, there were no significant differences in eggshell strength, eggshell thickness and eggshell color among the treatments, except for eggshell strength at 4 and 8 wk and eggshell thickness at 0 wk. In addition, no differences in egg yolk color and egg yolk index were found for all treatments throughout the 8-wk feeding period, except for egg yolk color at 0 wk. Thus, using various types of fermented red ginseng marc with red koji to laying hens did not improve eggshell and egg yolk quality characteristics.

• Journal of the Korean GEO-environmental Society
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• v.23 no.1
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• pp.5-13
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• 2022

In tropical regions, lateritic soil is frequently used in road embankment. However, it is one of the sources of road failure owing to its low strength. Generally, cement and lime are used as stabilizers for lateritic soil, but they are not environmentally friendly. Some studies try to use eggshells, for they are food waste and share the same chemical composition as lime. Previous researchs have shown that eggshell powder could enhance the strength of lateritic soil. This research investigated the effect of particle size of the eggshell powder and the effect of the protein-membrane presence in the eggshell on stabilizing capacity of soil. Through laboratory tests, unconfined compressive strength was examined for various particle sizes. The particle size of eggshell powder ranging between 150 ㎛ and 88 ㎛ was appropriate size that made an excellent stabilizer at 3% concentration. On the other hand, the protein-membrane reduced the stabilizing ability of the eggshell powder when the content of eggshell powder is less than 4% in soil. Numerical analysis of road embankment was performed based on the results obtained in the laboratory tests. It is shown that the eggshell powder has improved the stability of the sub-base of the road embankment.

• Food Science of Animal Resources
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• v.38 no.5
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• pp.1080-1091
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• 2018

The eggshell, which is a complex and highly ordered structure, is very important factor for food safety and egg marketing. This study investigated the changes in eggshell structure and shell components in relationship to hen age. For this study, we examined the histological change of the endometrium of the 30-, 60-, and 72-wk-old commercial layers, and analyzed the ultrastructure and ionic composition of their eggshells. The results showed that histological deformation, fibrosis, atrophy and elimination of micro-villi in the uterus endometrium were found through microscopic observation that was associated with increasing hen age. Concentration of blood-ion components such as $Ca^{2+}$, $Na^+$, $K^+$, and $Cl^-$ ions did not change with age. Along with the results from the ultrastructure analysis of the eggshell, the palisade layer ratio and the density of mammillary knobs were significantly decreased in older hens. In addition, the type B mammillary knobs were frequently observed with increasing hen age. In the mineral element assay from the eggshell, $Ca^{2+}$, $S^{2-}$, and $Co^{2+}$ significantly decreased with increasing hen age, whereas $Na^+$, $K^+$, and $V^{2+}$ significantly increased. Therefore, the damages of endometrial tissue inhibit the processes of ion transmission and the crystallization of eggshell formation, resulting in a large and non-uniform mammillary knob formation. This means the conditions of endometrial cells affect the formation of the eggshell structure. In conclusion, hen aging causes the weakness of the eggshell and degrades the eggshell quality.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.2
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• pp.162-168
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• 2010

This study attempted to clarify the difference in eggshell pigmentation between blue-shelled ducks (BSD) and whiteshelled ducks (WSD). The eggshell pigmentation deposition process is discussed. Ultraviolet spectro-photometer and HPLC were used to determine the biliverdin concentration in the shell gland, uterus liquid and eggshell at 6, 12, 18, 20, 23.5 h post-oviposition. The biliverdin concentration in the eggshell and uterus fluid showed significant differences between BSD and WSD, but not in the shell gland. The heme oxygenase activity in the shell gland of both kinds of ducks remained mostly constant during the ovulatory cycle with no variation. The assay of exogenous biliverdin injection into the shell gland antrum in the WSD indicated that exogenous biliverdin could be deposited continuously into the eggshell until the source was exhausted. A layer-by-layer dissolution assay was used to examine the eggshell pigment deposition process. The biliverdin concentration in the first to sixth layers of the eggshell in the BSD was significantly higher than that in the white-shelled counterpart. The blue pigment concentration increased persistently from the 6th layer to the $1^{st}$ layer. The BSD eggshells did not accumulate a large quantity of biliverdin in the most external layer. They tended to increase the deposition layer by layer. Our results demonstrated that different BSD and WSD eggshell colors were influenced by the amount of biliverdin in the uterus fluid and not determined by the amount of biliverdin in the shell gland. This implies the existence of a mechanism that controls biliverdin transportation from the shell gland into the uterus fluid, thereby playing a key role in regulating duck eggshell color.