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.

Cilj ovog rada je bio da ispita uticaj sistema gajenja, genotipa i starosti kokoši nosilja na masu i udeo glavnih delova jaja. Ispitivani sistemi gajenja su bili podni i organski, a ispitivani genotipovi Isa Brown hibrid i New Hampshire rasa. Jaja su sakupljana za analizu tri puta za vreme proizvodnog ciklusa (kod 32-nedeljnih nosilja, 48-nedeljnih i 72-nedeljnih). Na ovim uzorcima (15 jaja po grupi, jaja stara jedan dan) su ispitivani: masa jaja, udeo belanca, udeo žumanca i udeo ljuske jaja. Masa jaja se povećavala sa starenjem nosilja. Takođe, interakcija genotip x starost nosilja je bila značajna, pa su New hampshire kokoši u 32. nedelji nosile jaja manje mase od Isa Brown hibrida (p≤0.05), dok tih razlika u 48. i 72. nedelji nije bilo (p≥0.05). Udeo belanca i žumanca je bio od značajnim uticajem sistema gajenja, genotipa i starosti nosilja (p≤0.05). Podno gajenje kokoši su nosile jaja koja su imala manji udeo belanca a veći udeo žumanca u poređenju sa organskim kokošima (p≥0.05). Jaja New Hampshire rase su imala manji udeo belanca a veći udeo žumanca u poređenju sa Isa Brown genotipom (p≥0.05). Sa starenjem kokoši, udeo žumanca se povećavao a udeo belanca smanjivao. Interakcija sva tri ispitivana faktora - sistema gajenja, genotipa i starosti nosilja je imala najznačajniji uticaj na udeo ljuske jaja.