The eggshell quality of table eggs and how this affects food safety

Abstract

The longitudinal effect of age and production system was evaluated for egg quality parameters and egg microbial load by following 2 flocks (Hy Line brown commercial layer), one conventional cage production system (CC) and one free range (FR). A horizontal study of the effect of flock age (22, 39, 55 and 79 wk) of the same strain of bird from the same CC was also evaluated for egg quality parameters and egg microbial load. From the CC and FR production systems, eggs were collected at the age of 25, 35, 45, 55, 65 and 75 wk with one extra collection at 85 wk from CC. For the eggshell and egg internal quality parameters, a significant main effect (P<0.05) of flock age and production system or interaction between the two was recorded for egg translucency, shell reflectivity (%), egg weight (g), shell weight (g), percentage shell, shell thickness (μm), albumen height (mm), Haugh unit and yolk colour. Breaking shell strength (BSN) and shell deformation (μm) were only significantly affected by flock age and interaction between flock age and production system. In the horizontal study, all eggshell and egg internal quality variables were significantly affected by flock age.