THE PHENOTYPIC CORRELATION BETWEEN INTERNAL AND EXTERNAL EGG QUALITY TRAITS IN ISA BROWN COMMERCIAL LAYERS

Poultry farming is the raising of birds domestically or commercially, primarily for meat and eggs but also for feathers. Chickens, turkeys, ducks, and geese are of primary importance, while guinea fowl and squabs (young pigeons) are chiefly of local interest (Garrigus 2025). The global poultry industry is a critical contributor to food security and economic development, especially through the production of eggs, a highly nutritious and accessible source of animal protein. Egg production plays a pivotal role in the daily diets of millions and contributes significantly to agricultural GDP, especially in developing nations (FAO, 2021). As the demand for high-quality eggs continues to rise, the assessment and improvement of egg quality traits have become central to poultry breeding and management practices. Egg quality refers to the set of characteristics that define the acceptability of eggs to consumers and processors, and these characteristics are generally grouped into two main categories: external and internal traits. External traits include egg weight, shell thickness, shell color, and shape index, which affect consumer perception and handling characteristics. Internal traits include yolk weight, albumen height, yolk color, and Haugh unit, which are indicators of the egg’s nutritional and functional quality (Akinwumi et al., 2022).