ABSTRACT: To enhance production efficiency, the egg industry increasingly extends the laying cycle of hens. However, this extension exacerbates the decline in egg quality during the late laying period. To improve egg quality throughout the extended laying period of laying hens, this study analyzed 11 egg quality traits: eggshell strength (ESS), eggshell thickness (EST), eggshell weight (ESW), eggshell ratio (ESR), egg weight (EW), yolk weight (YW), yolk ratio (YR), egg shape index (EI), Haugh unit (HU), yolk color (YC), and eggshell membrane thickness (ESMT) in 2,577 White Leghorn hens across 35, 40, 50, 60, 70, 80, 90, and 100 wk of age. Phenotype and genetic parameter variations were systematically evaluated. Results showed that ESS, YC, and ESMT had low heritability (0.05-0.25), while ESW, ESR, E
