Occurrence and Genetic Parameters Estimation of Blood and Meat Spots in Brown-Shelled Eggs During the Extended Laying Period

Blood and meat spots are key internal egg quality indicators, and clarifying their genetic characteristics in late laying periods is critical for quality improvement via selective breeding. This study collected 392 eggs from 421 96-week-old Rhode Island Red hens across 69 families, analyzing 10 traits including blood/meat spots and standard egg quality traits. Heritability, genetic and phenotypic correlations were estimated using the DMU package. The incidences of blood and meat spots were 15.8% and 64.8%, respectively. Blood spots were yolk-localized, single and 2 mm). Blood spots had low heritability (0.05), meat spots moderate heritability (0.20). The two traits showed high positive genetic correlation (rG = 0.93), and strong negative genetic correlations with albumen height and eggshell strength. In conclusion, blood and meat spots in late-laying hens differ in distribution, size and number, and meat spots are amenable to genetic selection for internal egg quality enhancement.