Effect of Production System and Flock Age on Egg Quality

Abstract

Egg quality parameters were measured in eggs from flocks reared together and then allocated to different production systems. Eggs were processed for measurement of egg quality variables, scoring of ultrastructural mammillary layer features, completeness of cuticle cover and protoporphyrin IX (PPIX) quantification. There was a significant main effect (P<0.05) of production system on shell reflectivity, egg weight and egg internal quality and significant effects of flock age on most measurements. The mammillary layer ultrastructural variables showed no clear relationship with production system and flock age. Cuticle cover was significantly higher in barn eggs, followed by free range and cage eggs. Completeness of cuticle cover was significantly higher in eggs from the 44 week old flock than for 64 week and 73 week old flocks. There was a significant main effect of both production system and flock age, but no significant interaction for shell reflectivity, L* and amount of PPIX. There was no statistically significant difference for cuticle cover. In 1g of shell with and without cuticle, there was more PPIX in cage eggs followed by free range and barn eggs. Similar trends were recorded for the amount of PPIX in 1g of cuticle, but the difference was not statistically significant. The amount of PPIX decreased significantly with increasing flock age.