The Effect of Non-Genetic Parameters on Sex Determination

Abstract

From commercial, ethical and scientific perspectives, the culling of male chicks, particularly obtained from egg-laying breeders, is the most fundamental problem to be solved in the commercial poultry industry. This study aimed to determine the gender of the embryo based on characteristics of shell quality related to the weight of hatching eggs from broiler breeders. A total of 60 hatching eggs were divided into two groups: one weighing 55.50 g and the other weighing 66.50 g. The egg weight, width and length of air space, and width and length of each egg before incubation, and the water loss of the eggs during incubation was measured. At hatching, the weight of the chicks categorised by gender was measured, as well as the residual shell thickness, pore number, width and length of the pores. The difference in chick weight by gender is due to egg weight. Male and female chicks in the 66.50 EW group were heavier than those in the 55.50 EW group. Male chicks that hatched from heavier eggs were heavier than females. Male chicks hatched from thinner eggshells. Male chicks hatched from eggs with higher shape index, wider air space, smaller pore width at the pointed end and shorter pore lengths at the blunt and equatorial ends of lighter eggs. In contrast, female chicks hatched from eggs with lower shape index, higher shell thickness and wider pore width at the blunt, equatorial and pointed ends of lighter eggs, and with smaller air space width of heavier eggs. In conclusion, the gender of the embryo can be determined before or during embryo development based on various shell quality characteristics resulting from differences in egg weights obtained from broiler breeders of the same genotype and age.

Keywords

• egg
• egg quality
• embryo
• gender determination
• shell quality

References

1. Araújo, I. C. S. D., Leandro, N.S. M., Mesquita, M. A., Café, M. B., Mello, H. H. C., and Gonzales, E. (2017). Water Vapor Conductance: A Technique Using Eggshell Fragments and Relations with Other Parameters of Eggshell. Revista Brasileira de Zootecnia, 46 (12): 896-902. https://doi.org/10.1590/S1806-92902017001200004.
2. Arslan, E., Öztürk, R., Yonar, H., Kırıkçı, K., and Arslan, E. (2023). The Effect of Egg Shape Index on Pore Number and Hatching Performance in Susgender Hens. Journal of Istanbul Veterinary Sciences, 7 (3): 148-153. https://doi.org/10.30704/http-www-jivs-et.1378417
3. Aslam, M. A., Hulst, M., Hoving-Bolink, R. A., Smits, M. A., de Vries, B., Weites, I., Groothuis, T. G. G., and Woelders, H. (2013). Yolk Concentrations of Hormones and Glucose and Egg Weight and Egg Dimensions in Unincubated Chicken Eggs, In Relation to Egg Gender and Hen Body Weight. General and Comparative Endocrinology, 187: 15 - 22. https://doi.org/10.1016/j.ygcen.2013.02.045.
4. Babacanoğlu, E., Guler, H. C., Aktaş, A., and Yalçın. S. (2007). The Effects of Age and Water Losses during Incubation on Embryo Development and Certain Physiological Parameters in Broiler Breeders. In Proceeding of the 5th National Animal Science Congress, Van, Türkiye, September 2007.
5. Babacanoğlu, E. 2018. Responses of Developmental and Physiological Traits to Manipulated Incubation Conditions in Broiler Embryos at Hypoxic High Altitude. Archives Animal Breeding, 61 (3): 337-349. https://doi.org/10.5194/aab-61-337-2018.
6. Campo, J. L., and R. G. Ruano. (1995). Differences between Hatched and Non-Hatched Eggs for Weight Loss during Incubation, Shell Color, and Shape Index. European Poultry Science, 59: 310-313. https://doi.org/10.1016/S0003-9098(25)01380-3.
7. Cygan-Szczegielniak, D., and Bogucka, J. (2021). Growth Performance, Carcass Characteristics and Meat Quality of Organically Reared Broiler Chickens Depending on Gender. Animals, 11 (11): 3274. https://doi.org/10.3390/ani11113274.
8. Dunislawska, A., Siwek, M., Stadnicka, K., and Bednarczyk, M. (2021). Comparison of the Transcriptomic and Epigenetic Profiles of Gonadal Primordial Germ Cells of White Leghorn and Green-Legged Partridgelike Chicken Embryos. Genes, 12 (7): 1090. https://doi.org/10.3390/genes12071090.

9. Eratalar, S. A. (2023). Effects of Eggshell Thickness, Egg Weight and Shape Index on Hatch Window and Turkey Poults’ Gender. International Journal of Agricultural and Wildlife Sciences,9(3):490-496. https://doi.org/10.24180/ijaws.1310668
10. Etches, R. J. 1998. Reproduction in Poultry. Spain: Acribia, S. A.
11. Formanek, L, Richard‐Yris, M. A., Houdelier, C., and Lumineau, S. (2009). Epigenetic Maternal Effects on Endogenous Rhythms in Precocial Birds. Chronobiology International, 26(3):396-414. https://doi.org/10.1080/07420520902892433.
12. Göger, H. (2017). Sex Determination Methods of Chicks Before Hatching or Day-Old Age. Poultry Studies, 14, 013-019.
13. Kayadan, M. and Uzun, Y. (2023). High Accuracy Gender Determination Using the Egg Shape Index. Scientific Reports, 13(1): 504. https://doi.org/10.1038/s41598-023-27772-4
14. Krautwald-Junghanns, M. E., Cramer, K., Fischer, B., Förster, A., Galli, R., Kremer, F., Mapesa, E. U., Meissner, S., Preisinger, R., Preusse, G., Schnabel, C., Steiner, G., and Bartels, T. 2018). Current Approaches to Avoid the Culling of Day-Old Male Chicks in the Layer Industry, with Special Reference to Spectroscopic Methods. Poultry Science,97(3):749-757. https://doi.org/10.3382/ps/pex389.
15. Luo, X., Guo, J., Zhang, J., Ma, Z., and Li, H. (2024). Overview of Chicken Embryo Genes Related to Gender Differentiation. PeerJ, 12: e17072. http://doi.org/10.7717/peerj.17072.
16. Leenstra, F., Munnichs, G., Beekman, V., Van den Heuvel-Vromans, E., Aramyan, L., Woelders, H. (2011). Killing Day-Old Chicks? Public Opinion Regarding Potential Alternatives. Animal Welfare, 20 (1): 37-45. https://doi.org/10.1017/S0962728600002414.
17. Lv, X., Sun, C., Liu, X., Liu, G., Gong, W., Qian, H., Li, Z., Wu, J., Zhu, X., Song, J., Niu, Y., Sun, H., Han, W., Chen, G. H., Jin, K., Li, B., and Zuo, Q. (2025). Key Events in the Process of Gender Determination and Differentiation in Early Chicken Embryos. Animal Bioscience, 38(6): 1081–1104. https://doi.org/10.5713/ab.24.0679.
18. Peebles, E. D., and Mcdaniel, C. D. (20049. A Practical Manual for Understanding the Shell Structure of Broiler Hatching Eggs and Measurements of Their Quality. Mississippi Agriculture and Forestry Experiment Station Bulletin, 1139: 16.
19. Roque, L, and Soares, M. C. (1994). Effects of Eggshell Quality and Broiler Breeder Age on Hatchability. Poultry Science, 73 (12): 1838-1845. https://doi.org/10.3382/ps.0731838. SAS. (2009). SAS/STAT User’s Guide, Version 9.1.3. SAS Institute Inc. Cary. NC.
20. Shanawany, M. M. (1984). Inter‐relationship between Egg Weight, Parental Age and Embryonic Development. British Poultry Science, 25(4): 449-455. https://doi.org/10.1080/00071668408454886. Shanawany, M. M. (1987). Hatching Weight in Relation to Egg Weight in Domestic Birds. World's Poultry Science Journal, 43 (2): 107-115. https://doi.org/10.1079/WPS19870008.
21. Stadelman, W. J. Newkırk, D., and Newby, L. (2017). Egg Science and Technology: Quality Identification of Shell Eggs. England: CRC Press.
22. Şekeroǧlu, A., and Altuntaş, E. (2009). Effects of Egg Weight on Egg Quality Characteristics. Journal of the Science of Food and Agriculture, 89(3): 379-383. http://www.interscience.wiley.com/jsfa. Tserveni-Gousi, A. S., and Yannakopoulos, A. L. (1990). Quality Characteristics of Pheasant Eggs and Effect of Egg Weight and Shell Quality on Chick Weight. European Poultry Science, 54(2): 54-56. https://doi.org/10.1016/S0003-9098(25)01468-7.
23. Tunç, J., and Babacanoğlu Çakır, E. (2024). Prediction of gender by the effect of gender genes on phenotypic traits. In, Proceeding of the 7th International Cukurova Agriculture and Veterinary Congress, Adana, Türkiye, March 2024.
24. Werren, J. H., and Hatcher, M. J. (2000). Maternal-Zygotic Gene Conflict Over Gender Determination: Effects of Inbreeding. Genetics, 155 (3): 1469-1479. doi: 10.1093/genetics/155.3.1469.
25. Wilson, H. R. (1991). Interrelationships of Egg Size, Chick Size, Posthatching Growth and Hatchability. World's Poultry Science Journal, 47(1): 5-20. https://doi.org/10.1079/WPS19910002.
26. Xu, S., Chen, J., Long, S., Lin, H., Xie, L., and Pan, J. (2025). Multi-Omics Analysis of Yolk and Allantoic Fluid in Chicken Embryonic Development and Genderual Differentiation. Poultry Science, 105349. https://doi.org/10.1016/j.psj.2025.105349.