Simple Summary
This review synthesizes recent progress on the genetic and epigenetic determinants of poultry egg quality. It covers external traits (shell thickness, color, strength) and internal traits (albumen height, yolk composition, Haugh unit), outlining how QTL/GWAS, WGS, and multi-omics have mapped candidate genes and pathways for shell biomineralization, albumen protein regulation, and yolk lipid transport. It summarizes heritability patterns across traits and ages, highlights regulatory biology of follicular development and calcium transport, and details epigenetic layers (DNA methylation, histone marks, RNA methylation, post-translational protein modifications). This paper emphasizes translation to breeding via genomic selection and marker-assisted strategies, while noting polygenic architecture and environmental interactions as key challenges. It concludes with prospects for integrative, single-cell, and epigenetic engineering approaches to develop precision breeding programs and value-added “functional” eggs.
Abstract
Egg quality is a critical economic trait in poultry production, influencing consumer preference and production efficiency. The genetic and epigenetic regulation of egg quality involves complex biological pathways across various traits such as shell quality, albumen composition, and yolk biochemistry. This review synthesizes recent advances in the genetic, molecular, and epigenetic mechanisms that determine poultry egg quality. Specifically, it focuses on external traits such as eggshell strength, color, and thickness, and internal traits including albumen height, yolk composition, and the Haugh unit. Through genome-wide association studies (GWAS), quantitative trait loci (QTL) mapping, whole-genome sequencing (WGS), and multi-omics approaches, key candidate genes such as OC-116, CALB1, CA2 (shell formation), OVAL, SPINK5, SERPINB14 (albumen quality), and FGF9, PIAS1, NOX5 (lipid metabolism) have been identified. These genes play a pivotal role in shell biomineralization, albumen protein regulation, and yolk lipid transport. This review also explores the heritability of these traits, emphasizing the challenges posed by polygenic architecture and the influence of environmental factors. Furthermore, it addresses the dynamic spatiotemporal regulation of egg quality traits, including epigenetic layers such as DNA methylation, histone modifications, RNA methylation, and post-translational protein modifications. This paper highlights the application of these findings to breeding programs via genomic selection, marker-assisted breeding, and epigenetic engineering approaches. Future directions for precision breeding and the development of functional eggs with enhanced quality are also discussed.