The effect of the rearing system, genotype and laying hens age on the egg weight and share of main parts of eggs

Abstract

The aim of this study was to evaluate the effect of rearing system, genotype and hens age on egg weight and eggs components share. The tested rearing systems were the floor and organic, and tested genotypes were Isa Brown hybrid and New Hampshire breed. Eggs were collected for analyses three times in production cycle (32 weeks hens age, 48 weeks hens age, and 72 weeks hens age). In these samples (fifteen eggs per group, eggs were one day old) were investigated: egg weight, albumen share, yolk share and shell share. Egg weight was increased with hens age. Also, the interaction between the genotype and hens age was found, so the New Hampshire eggs in 32 weeks had less weight then Isa Brown eggs (p≤0.05), while in the 48 and 72 weeks this difference was lost (p≥0.05).  The share of egg albumen and yolk was significantly affected by the rearing system, genotype and hens age (p≤0.05). Floor produced eggs had a lower proportion of albumen and a higher proportion of yolk compared to organic eggs. New Hampshire eggs had a higher content of yolk and the smaller content of albumen compared to Isa Brown eggs (p≤0.05). With hens age, the share of yolk was increased and albumen share was decreased. Interaction of all three studied factors - rearing system x genotype x hens age had the most important effect on the shell share.