The Effect of Age of Laying Hens on Egg Composition and Egg Quality in Close Housing System

Abstract

The impact of age on egg composition and quality in commercial laying hens was investigated. Data regarding egg production were collected from a flock of 1,002 laying hens (comprising 334 cages) between 26 and 58 weeks of age. Twenty eggs were randomly collected from 20 cages monthly over 8 months on 9 sampling occasions (n = 180) to assess egg composition and quality. Egg production and quality data collected over 8 consecutive months were analyzed using ANOVA under the General Linear Model (GLM), with hen age as the experimental factor. Mean comparisons were performed using Tukey’s HSD at p < 0.05, and correlations among egg quality traits were analyzed. Results indicated that hen-day egg production was not significantly affected by hen age. However, mean egg weight increased (p < 0.05) with hen age, resulting in a shift in egg size classification from size no. 3 to size no. 1. Regarding egg components, yolk weight, albumen weight, yolk ratio, and yolk-to-albumen ratio increased (p < 0.05) with age, whereas albumen ratio and shell strength decreased (p < 0.05). Concerning egg quality parameters, albumen height and Haugh unit values declined (p < 0.05) with increasing hen age. In conclusion, while egg production remained consistent across the age range studied, advancing age in commercial laying hens was associated with increases in egg size and yolk proportion, concomitant with reductions in albumen height and Haugh unit, indicative of declining egg quality.