台灣養鴨產業發達，其中鴨蛋產品主要以加工方式呈現，因而產生大量的蛋殼廢棄物，目前國內廢棄鴨蛋殼多以焚化方式處理，而雞蛋殼的產量較大，多半以壓碎製成堆肥使用。本研究期望於廢棄蛋殼中開發出具有高經濟價值的保健成分，以提高畜產加工業的經濟效益。
本論文目標有二：由青蛋殼中萃取出具有抗氧化活性的成分物質，已知青蛋殼中含有膽綠素，而膽綠素已被證實具有抗氧化、抗突變與抗發炎等生理活性，本試驗預期由靑蛋殼中開發出具有活性的膽綠素或其他有效抗氧化成分。再者，本研究對民間流傳的青殼蛋具有抗腫瘤之說感到興趣，期望能由青蛋殼萃取物中開發出具抗癌新藥之物質。
在本試驗過程中，已建立一有效的萃取流程，不僅可分離出含有抗氧化活性的蛋殼抽提液，而且於加工後具有抗肝臟腫瘤的功能。進行靑蛋殼中有效成分之抽提，並以光電比色計吸光測試與 HPLC 分析，證實其中含有膽綠素成分。繼之，將蛋殼抽提液進行三種抗氧化能力測試：清除 DPPH 能力、SOD-like 活性與抑制脂質過氧化物能力等。結果顯示：青蛋殼抽提液具有明顯抑制脂質過氧化物的能力，而白蛋殼抽提液則否，推論為膽綠素成分所致；在 SOD-like 活性測試中，靑蛋殼與白蛋殼抽提液兩者皆具有活性，故推測 SOD-like 的活性是由蛋殼抽提液中非膽綠素的其他抗氧化成份所影響。至於清除 DPPH 的能力，則青、白蛋殼抽提液兩者皆無。
再者，進一步將蛋殼抽提液進行加工處理，發現活化的蛋殼萃取物對於肝臟腫瘤細胞株 HepG2 與 huh 7 均具顯著性的抑制效果，其中又以 huh 7之感受性最強。然而，對於鼠胚的初代纖維母細胞 (MEF) 與人類幹細胞株 (HBM01) 的抑制作用則顯著較低 (p < 0.001)。當更深入探討抗腫瘤的作用機制時，發現活化的蛋殼萃取物會導致肝臟腫瘤細胞 huh 7 的粒線體活性降低，並且提升細胞內Caspase-9 與 Caspase-3 的活性，進而導致 huh 7 細胞進行自體凋亡 (apoptosis)。總結上述：本論文為首次發表蛋殼萃取物中具有抗氧化與抗腫瘤之研究，預期將來可由蛋殼萃取物中開發出具有高經濟價值的保健成分或抗癌新藥。

The duck industry is vigorously developed in Taiwan. However, the by-product of eggshell is wasted and may cause the environmental pollution. In order to re-utilize the waste to raise the economical value, we tried to extract the high valuable component from the eggshell. Based on the traditional Chinese medicine, the blue egg shell has been believed to be an important medicine-inducer. Some reports indicated that the pigment of blue egg was biliverdin. Biliverdin has been proven to be an important antioxidant, anti-mutagen and immunoregulator in physiology. We considered that there should be some antioxidants existed in blue eggshell, especially biliverdin.
There were two major objectives in the present study, which were to extract the antioxidative activities of biliverdin and other substrates from blue eggshell, and to assay the anti-tumor ability of the extract. In this study, we obtain the crude extract of eggshell. The biliverdin component in the crude extract was detected by spectrophotometer and by HPLC. Also, the crude extract of blue eggshell has been proven to have the antioxidative ability to prevent the lipid peroxideation, but that of white eggshell didn’t. Moreover, the crude extract was concentrated by vacuum and then heated to be the active extract. The active extract after heating process has been found to strongly inhibit the proliferation and induce the apoptosis of liver tumor cell lines, huh 7 and Hpe G2, especially huh 7. However, the cytotoxicity was much lower to the human bone marrow cell (HBM 01) and the primary culture of mouse embryonic fibroblasts. Also, we proved that the heated eggshell extract could cause huh 7 apoptosis by triggering the pathway of Caspase-9 and Caspase-3 caused by the depolarization of mitochondria.
It is the first time to find the anti-tumor complex existed in eggshell in this study. It may be valuable to develop a new anti-tumor drug from the heated extract of eggshell in the future.

中文摘要 04
英文摘要 06
圖次 07
附圖次 09
附表次 10
壹、前言 11
貳、文獻檢討 13
一、蛋殼生產與再利用 13
(一)、台灣養鴨產業與青殼鴨蛋的生產 13
(二)、蛋殼之形成 15
(三)、蛋殼色素之形成 18
(四)、蛋殼顏色對經濟性狀之影響 21
(五)、蛋殼成分的再利用 24
二、膽綠素 27
(一)、膽汁色素的生理代謝 27
(二)、膽綠素的生理活性 32
參、材料與方法 44
一、試驗大綱 44
二、蛋殼有效成分抽提與萃取 46
(一)、樣品挑選 46
(二)、蛋殼前處理 46
(三)、蛋殼酸解 47
(四)、蛋殼酸解液之液相抽提 47
(五)、真空減壓濃縮 48
(六)、樣品測試 48
三、靑蛋殼抽提液之保健成分分析 49
(一)、蛋殼抽提液之可見光吸光值分析 49
(二)、蛋殼抽提液之高壓液相層析儀分析 49
四、靑蛋殼抽提液之抗氧化能力測定 50
(一)、清除 DPPH 能力之測定 50
(二)、清除超氧化陰離子能力測定 51
(三)、抗脂質氧化能力測定 52
五、活化蛋殼萃取物抗腫瘤能力之測定 53
(一)、細胞培養 54
(二)、細胞染色與型態觀測 55
(三)、細胞存活率測試 56
(四)、細胞自體凋亡測試 57
六、統計分析 61
肆、結果 62
一、靑蛋殼膽綠素萃取與分析 62
(一)、建立膽綠素測定指標 62
(二)、建立最佳之青蛋殼酸解方法 62
(三)、建立最佳之青蛋殼抽提方法 63
(四)、靑蛋殼抽提液之HPLC圖譜分析 64
二、抗氧化能力測定 65
(一)、清除DPPH能力之測定 65
(二)、清除超氧陰離子能力之測定 65
(三)、清除脂質過氧化物能力之測定 65
三、抗腫瘤能力之測定 67
(一)、活化蛋殼萃取物抑制腫瘤細胞能力之研究 69
(二)、活化蛋殼萃取物影響細胞自體凋亡之測定 70
伍、討論 72
陸、結論 80
柒、參考文獻 81
捌、附錄 104

王政騰、萬添春、潘金木、鄭永祥。1997。褐色菜鴨青白殼蛋之理化性狀及鹼化過程比較。中國農業化學會誌。35(3)：263～272。
王錦盟。2007。營養對蛋殼的影響。飼料營養雜誌。96(6)：20～26。
朱吉川。1997。肉骨粉之鈣、磷比。飼料營養雜誌。86(9)：74～75。
林榮新、杜素豪、黃振芳、劉秀洲、胡怡浩、陳添福。2006。消費者對一般鴨蛋及青殼鴨蛋的認知與購買傾向之研究。39(3)：149～163。
胡怡浩、劉秀洲、廖奕雯、潘金木。2002。褐色菜鴨品系間與家族間蛋殼顏色變異之探討。畜產研究。35(3)：232～240。
黃振芳、林佳靜。1997。1997國際雞蛋研討會簡介。中國畜牧雜誌。30(9)：48～51。
黃暉煌。2001。鴨的品種。中國畜牧學會畜牧要覽，家禽篇 (增修版)。PP. 26-27。台北市，華香園。
許瑞沛。1989。由豬膽汁中分離純化膽紅素。碩士論文。台灣大學。
潘金木。1993。本地菜鴨青殼蛋的分布與結構之探討。畜牧專訊 4：7～8。
葉志河。1992。從豬膽汁中萃取純化膽紅素。碩士論文。台灣大學。
劉秀洲、陳得財、黃振芳、胡怡浩。2001。褐色菜鴨靑蛋品系選育I . 族群建立。畜產研究。34(3)：265～270。
劉秀洲、黃振芳、孫自力、李舜榮、王政騰。1998。褐色菜鴨青殼蛋之遺傳特性。畜產研究。31(4)：373～382。
Aberg, F., E. L. Appelkvist, G. Dallner, and L. Ernster. 1992. Distribution and redox state of ubiquinones in rat and human tissues. Arch Biochem Biophys 295: 230-234.
Alam, J. 2002. Heme oxygenase-1: Past, present, and future. Antioxid Redox Signal 4: 559-562.
Alcaraz, M. J., P. Fernandez, and M. I. Guillen. 2003. Anti-inflammatory actions of the heme oxygenase-1 pathway. Curr Pharm Des 9: 2541-2551.
Ames, B. N., J. McCann, and E. Yamasaki. 1975. Proceedings: Carcinogens are mutagens: A simple test system. Mutat Res 33: 27-28.
Arias, J. L., M. S. Fernandez, J. E. Dennis, and A. I. Caplan. 1991. The fabrication and collagenous substructure of the eggshell membrane in the isthmus of the hen oviduct. Matrix 11: 313-320.
Baranano, D. E., M. Rao, C. D. Ferris, and S. H. Snyder. 2002. Biliverdin reductase: A major physiologic cytoprotectant. Proc Natl Acad Sci U S A 99: 16093-16098.
Belizna, C. C., V. Richard, C. Thuillez, H. Levesque, and Y. Shoenfeld. 2007. Insights into atherosclerosis therapy in antiphospholipid syndrome. Autoimmun Rev 7: 46-51.
Bitgood, J. J., R. W. Briles, and W. E. Briles. 2000. Further tests for genetic linkages of three morphological traits, three blood groups, and break points of two chromosome translocations on chromosome one in the chicken. Poult Sci 79: 293-295.
Bowie, A., and L. A. O'Neill. 2000. Oxidative stress and nuclear factor-kappab activation: A reassessment of the evidence in the light of recent discoveries. Biochem Pharmacol 59: 13-23.
Brodersen, R. 1979. Bilirubin. Solubility and interaction with albumin and phospholipid. J Biol Chem 254: 2364-2369.
Bulmer, A. C., K. Ried, J. T. Blanchfield, and K. H. Wagner. 2008. The anti-mutagenic properties of bile pigments. Mutat Res 658: 28-41.
Bulmer, A. C., K.Ried, J. S. Coombes, J. T. Blanchfield, I. Toth, and K. H.Wagner. 2007. The anti-mutagenic and antioxidant effects of bile pigments in the ames salmonella test. Mutat Res 629: 122-132.
Canzi, C., F. Zito, F. Voltini, E. Reschini, and P. Gerundini. 2006. Verification of the agreement of two dosimetric methods with radioiodine therapy in hyperthyroid patients. Med Phys 33: 2860-2867.
Chen, Y. L., S. Z. Lin, J. Y. Chang, Y. L. Cheng, N. M. Tsai, S. P. Chen, W. L. Chang, and H. J. Harn. 2006. In vitro and in vivo studies of a novel potential anticancer agent of isochaihulactone on human lung cancer a549 cells. Biochem Pharmacol 72: 308-319.
Cho, Y. S., S. T. Hong, K. H. Choi, Y. H. Chang, and A. S. Chung. 2000. Chemopreventive activity of porphyrin derivatives against 6-sulfooxymethylbenzo[a]pyrene mutagenicity. Asian Pac J Cancer Prev 1: 311-317.
Cohen, G. M. 1997. Caspases: The executioners of apoptosis. Biochem J 326 ( Pt 1): 1-16.
De Flora, S., A. Izzotti, K. Randerath, E. Randerath, H. Bartsch, J. Nair, R. alansky, F. Schooten, P. Degan, G. Fronza, D. Walsh, and J. Lewtas. 1996. DNA adducts and chronic degenerative disease. Pathogenetic relevance and implications in preventive medicine. Mutat Res 366: 197-238.
Dieckert, J. W., M. C. Dieckert, and C. R. Creger. 1989. Calcium reserve assembly: A basic structural unit of the calcium reserve system of the hen egg shell. Poult Sci 68: 1569-1584.
Farinati, F., R. Cardin, V. M.Russo, G. Busatto,M. Franco, and M. Rugge. 2003. Helicobacter pylori caga status, mucosal oxidative damage and gastritis phenotype: A potential pathway to cancer? Helicobacter 8: 227-234.
Fernandez Lopez, J. C., and A. Ruano-Ravina. 2006. Efficacy and safety of intraarticular hyaluronic acid in the treatment of hip osteoarthritis: A systematic review. Osteoarthritis Cartilage 14: 1306-1311.
Fevery, J., N. Blanckaert, P. Leroy, R. Michiels, and K. P. Heirwegh. 1983. Analysis of bilirubins in biological fluids by extraction and thin-layer chromatography of the intact tetrapyrroles: Application to bile of patients with gilbert's syndrome, hemolysis, or cholelithiasis. Hepatology 3: 177-183.
Fondevila, C., X. D.Shen, S. Tsuchiyashi, K. Yamashita, E. Csizmadia, C. Lassman, R. W.Busuttil, J. W.Kupiec-Weglinski, and F. H.Bach. 2004. Biliverdin therapy protects rat livers from ischemia and reperfusion injury. Hepatology 40: 1333-1341.
Gautron, J., M. T.Hincke, M. Panheleux, J. M.Garcia-Ruiz, T. Boldicke, and Y.Nys. 2001. Ovotransferrin is a matrix protein of the hen eggshell membranes and basal calcified layer. Connect Tissue Res 42: 255-267.
Gibbs, P. E., and M. D. Maines. 2007. Biliverdin inhibits activation of nf-kappab: Reversal of inhibition by human biliverdin reductase. Int J Cancer 121: 2567-2574.
Halliwell, B. 1999. Antioxidant defence mechanisms: From the beginning to the end (of the beginning). Free Radic Res 31: 261-272.
Hincke, M. T. 1995. Ovalbumin is a component of the chicken eggshell matrix. Connect Tissue Res 31: 227-233.
Kamisako, T., Y. Kobayashi, K. Takeuchi, T. Ishihara, K. Higuchi, Y. Tanaka, E. C. Gabazza, and Y. Adachi. 2000. Recent advances in bilirubin metabolism research: The molecular mechanism of hepatocyte bilirubin transport and its clinical relevance. J Gastroenterol 35: 659-664.
Katoh, Y., N. Nemoto, M. Tanaka, and S. Takayama. 1983. Inhibition of benzo[a]pyrene-induced mutagenesis in chinese hamster v79 cells by hemin and related compounds. Mutat Res 121: 153-157.
Kaur, H., M. N.Hughes, C. J.Green, P. Naughton, R. Foresti, and R. Motterlini. 2003. Interaction of bilirubin and biliverdin with reactive nitrogen species. FEBS Lett 543: 113-119.
Kelloff, G. J., C. W. Boone, J. A. Crowell, V. E. Steele, R. Lubet, and C. C. Sigman. 1994a. Chemopreventive drug development: Perspectives and progress. Cancer Epidemiol Biomarkers Prev 3: 85-98.
Kelloff, G. J., J. A. Crowell, C. W. Boone, V. E. Steele, R. A. Lubet, P. Greenwald, D. S. Alberts, J. M. Covey, L. A. Doody, and G. G. Knapp. 1994b. Strategy and planning for chemopreventive drug development: Clinical development plans. Chemoprevention branch and agent development committee. National cancer institute. J Cell Biochem Suppl 20: 55-62.
Kennedy, G. Y., and H. G. Vevers. 1973. Eggshell pigments of the araucano fowl. Comp Biochem Physiol B 44: 11-25.
Kennedy, G. Y., and H. G. Vevers. 1976. A survey of avian eggshell pigments. Comp Biochem Physiol B 55: 117-123.
Keshavan, P., S. J. Schwemberger, D. L. Smith, G. F. Babcock, and S. D. Zucker. 2004. Unconjugated bilirubin induces apoptosis in colon cancer cells by triggering mitochondrial depolarization. Int J Cancer 112: 433-445.
Lafarge-Frayssinet, C., E. Morel-Chany, G. Trincal, and C. Frayssinet. 1981. Enhancement of DNA synthesis by biliverdin in a non-transformed liver cell strain. Cell Mol Biol Incl Cyto Enzymol 27: 77-82.
Lafarge-Frayssinet, C., E. Morel-Chany, G. Trincal, and C. Frayssinet. 1983. Promoting effect of biliverdin for liver cells initiated by aflatoxin b1. Cancer Lett 18: 277-282.
Li Volti, G., L. F.Rodella, C. Di Giacomo, R. Rezzani, R. Bianchi, E. Borsani, D. Gazzolo, and R. Motterlini. 2006. Role of carbon monoxide and biliverdin in renal ischemia/reperfusion injury. Nephron Exp Nephrol 104: e135-139.
Lissi, E. A., B. Modak, R. Torres, J. Escobar, and A. Urzua. 1999. Total antioxidant potential of resinous exudates from heliotropium species, and a comparison of the abts and dpph methods. Free Radic Res 30: 471-477.
Los, M., M. Mozoluk, D. Ferrari, A. Stepczynska, C. Stroh, A. Renz, Z. Herceg, Z. Q.Wang, and K. Schulze-Osthoff. 2002. Activation and caspase-mediated inhibition of parp: A molecular switch between fibroblast necrosis and apoptosis in death receptor signaling. Mol Biol Cell 13: 978-988.
McCord, J. M., and I. Fridovich. 1969. Superoxide dismutase. An enzymic function for erythrocuprein (hemocuprein). J Biol Chem 244: 6049-6055.
McPhee, F., P. S. Caldera, G. W. Bemis, A. F. McDonagh, I. D. Kuntz, and C. S. Craik. 1996. Bile pigments as hiv-1 protease inhibitors and their effects on hiv-1 viral maturation and infectivity in vitro. Biochem J 320 ( Pt 2): 681-686.
Mine, Y., C. Oberle, and Z. Kassaify. 2003. Eggshell matrix proteins as defense mechanism of avian eggs. J Agric Food Chem 51: 249-253.
Mori, H., T. Otake, M. Morimoto, N. Ueba, N. Kunita, T. Nakagami, N. Yamasaki, and S. Taji. 1991. In vitro anti-human immunodeficiency virus type 1 activity of biliverdin, a bile pigment. Jpn J Cancer Res 82: 755-757.
Mortelmans, K., and E. Zeiger. 2000. The ames salmonella/microsome mutagenicity assay. Mutat Res 455: 29-60.
Moscowitz, A., M. Weimer, D. A.Lightner, Z. J.Petryka, E. Davis, and C. J. Watson. 1971. The in vitro conversion of bile pigments to the urobilinoids by a rat clostridia species as compared with the human fecal flora. 3. Natural d-urobilin, synthetic i-urobilin, and synthetic i-urobilinogen. Biochem Med 4: 149-164.
Nakagami, T., K. Toyomura, T. Kinoshita, and S. Morisawa. 1993. A beneficial role of bile pigments as an endogenous tissue protector: Anti-complement effects of biliverdin and conjugated bilirubin. Biochim Biophys Acta 1158: 189-193.
Nakano, T., N. Ikawa, and L. Ozimek. 2001. Extraction of glycosaminoglycans from chicken eggshell. Poult Sci 80: 681-684.
Nakano, T., N. Ikawa, and L. Ozimek. 2002. Galactosaminoglycan composition in chicken eggshell. Poult Sci 81: 709-714.
Pahl, H. L. 1999. Activators and target genes of rel/nf-kappab transcription factors. Oncogene 18: 6853-6866.
Rovensky, J., M. Stancikova, P. Masaryk, K. Svik, and R. Istok. 2003. Eggshell calcium in the prevention and treatment of osteoporosis. Int J Clin Pharmacol Res 23: 83-92.
Sass, G., K. Koerber, R. Bang, H. Guehring, and G. Tiegs. 2001. Inducible nitric oxide synthase is critical for immune-mediated liver injury in mice. J Clin Invest 107: 439-447.
Sass, G., S. Seyfried, M. Parreira Soares, K. Yamashita, E. Kaczmarek, W. L. Neuhuber, and G. Tiegs. 2004. Cooperative effect of biliverdin and carbon monoxide on survival of mice in immune-mediated liver injury. Hepatology 40: 1128-1135.
Schaafsma, A., J. J. van Doormaal, F. A.Muskiet, G. J.Hofstede, I. Pakan,
and E. van der Veer. 2002. Positive effects of a chicken eggshell powder-enriched vitamin-mineral supplement on femoral neck bone mineral density in healthy late post-menopausal dutch women. Br J Nutr 87: 267-275.
Schwartz, S., W. A. Raux, B. A. Schacter, B. D. Stephenson, and R. N. Shoffner. 1980. Loss of hereditary uterine protoporphyria through chromosomal rearrangement in mutant rhode island red hens. Int J Biochem 12: 935-940.
Sedlak, T. W., and S. H. Snyder. 2004. Bilirubin benefits: Cellular protection by a biliverdin reductase antioxidant cycle. Pediatrics 113: 1776-1782.
Sluyter, R., and G. M. Halliday. 2001. Infiltration by inflammatory cells required for solar-simulated ultraviolet radiation enhancement of skin tumor growth. Cancer Immunol Immunother 50: 151-156.
Soler, J. J., J. Moreno, J. M. Aviles, and A. P. Moller. 2005. Blue and green egg-color intensity is associated with parental effort and mating system in passerines: Support for the sexual selection hypothesis. Evolution Int J Org Evolution 59: 636-644.
Stocker, R. 2004. Antioxidant activities of bile pigments. Antioxid Redox Signal 6: 841-849.
Stocker, R., A. N. Glazer, and B. N. Ames. 1987. Antioxidant activity of albumin-bound bilirubin. Proc Natl Acad Sci U S A 84: 5918-5922.
Stocker, R., A. F. McDonagh, A. N. Glazer, and B. N. Ames. 1990. Antioxidant activities of bile pigments: Biliverdin and bilirubin. Methods Enzymol 186: 301-309.
Stocker, R., and E. Peterhans. 1989a. Antioxidant properties of conjugated bilirubin and biliverdin: Biologically relevant scavenging of hypochlorous acid. Free Radic Res Commun 6: 57-66.
Stocker, R., and E. Peterhans. 1989b. Synergistic interaction between vitamin e and the bile pigments bilirubin and biliverdin. Biochim Biophys Acta 1002: 238-244.
Tang, X., and R. Edenharder. 1997. Inhibition of the mutagenicity of 2-nitrofluorene, 3-nitrofluoranthene and 1-nitropyrene by vitamins, porphyrins and related compounds, and vegetable and fruit juices and solvent extracts. Food Chem Toxicol 35: 373-378.
Wang, C. P., X. J. Liu, I. Ohnuma, R. Kainuma, and K. Ishida. 2002a. Formation of immiscible alloy powders with egg-type microstructure. Science 297: 990-993.
Wang, X., B. C. Ford, C. A. Praul, and R. M. Leach, Jr. 2002b. Collagen x expression in oviduct tissue during the different stages of the egg laying cycle. Poult Sci 81: 805-808.
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. Poult Sci 86: 2236-2238.
Wellman-Labadie, O., J. Picman, and M. T. Hincke. 2008a. Antimicrobial activity of cuticle and outer eggshell protein extracts from three species of domestic birds. Br Poult Sci 49: 133-143.
Wellman-Labadie, O., J. Picman, and M. T. Hincke. 2008b. Antimicrobial activity of the anseriform outer eggshell and cuticle. Comp Biochem Physiol B Biochem Mol Biol 149: 640-649.
Westmoreland, D., R. W. Krell, and B. P. Self. 2007. Physiological responses to the coriolis illusion: Effects of head position and vision. Aviat Space Environ Med 78: 985-989.
Wu, Q., Y. Chen, and X. G. Li. 2005. [effect of curcumin on caspase 8- and caspase 9- induced apoptosis of lymphoma raji cell]. Zhongguo Shi Yan Xue Ye Xue Za Zhi 13: 624-627.
Yamashita, K., J.McDaid, R.Ollinger, T. Y.Tsui, P. O.Berberat, A.Usheva, E.Csizmadia, R. N.Smith, M. P.Soares, and F. H. Bach. 2004. Biliverdin, a natural product of heme catabolism, induces tolerance to cardiac allografts. FASEB J 18: 765-767.
Zakeri, Z., W. Bursch, M. Tenniswood, and R. A. Lockshin. 1995. Cell death: Programmed, apoptosis, necrosis, or other? Cell Death Differ 2: 87-96.
Zhang, L. C., Z. H. Ning, G. Y. Xu, Z. C. Hou, and N. Yang. 2005. Heritabilities and genetic and phenotypic correlations of egg quality traits in brown-egg dwarf layers. Poult Sci 84: 1209-1213.
Zhao, R., G. Y. Xu, Z. Z. Liu, J. Y. Li, and N. Yang. 2006. A study on eggshell pigmentation: Biliverdin in blue-shelled chickens. Poult Sci 85: 546-549.