TIME OF OVIPOSITION AND EGG COMPOSITION: A REVIEW

Time of oviposition depends on several factors, which include changes in lighting regime. Hens lay their eggs generally 6 hours after switching on the light. The earlier turn on, causes laying of majority of eggs in the early morning. Oviposition time affects characteristics of egg quality, especially weight of egg and shell quality. Eggs laid in the morning are heavier. However, eggs laid in the afternoon have better quality of eggshell. Time of oviposition and egg weight depends on genotype of hens as well. Brown eggs tend to be laid in the morning and they are heavier than white and tinted eggs, that are lighter and tend to be laid in the afternoon. Albumen weight and Haugh units decline, but yolk weight increased with oviposition time. Also housing system influences oviposition time. Genotype, housing system and oviposition time significantly affect egg weight and Haugh units, the characteristic of internal egg quality. An understanding of range of factors that affect egg quality is necessary for the production of egg of high quality. Egg quality vary according to interactions between all mentioned factors