EFFECT OF EGG SIZE AND STRAIN AND AGE OF HENS ON THE SOLIDS CONTENT OF CHICKEN EGGS

A study was conducted to determine the effect of egg size and the age and strain of hens on the content of egg solids. Eggs were obtained. f rom commercial farms from four strains of hens with similar age groups and received diets formulated to contain the same dietary energy and protein levels across the strains within a farm. Eggs were collected o n 2 different d when the flocks reached the average ages of 28, 55, 75 , and 97 wk. The eggs collected from each farm were pooled and sorted by size. Each individual egg was used as a replicate for yolk:white ra tio; however, five yolks, five whites, and five whole eggs from each s train at each age period were pooled, homogenized, and then used as a replicate to determine the solids contents of yolk, white, and whole e ggs. The yolk:white ratio of eggs from 28-wk-old hens was the lowest, that from 55- and 78-wk-old hens was the highest, and that from 97-wk- old hens was intermediate; however, the solids content (percentage) of whole eggs increased with the age of the hens. The solids content of egg white was highest in eggs from 28-wk-old hens. The white solids co ntent of extra large eggs was greater than that of medium eggs, and yo lk solids increased with egg size; however, the solids of whole egg we re not affected by egg size. The strain of hens had a significant effe ct on the solids of whole egg,white, and yolk; however, the strain eff ect on yolk:white ratio was not significant. The results showed that y oung (28-wk-old) and old birds (97-wk-old) produced eggs with low soli ds content and intermediate aged hens (55- to 78-wk-old) produced eggs with high solids content. Therefore, it may be more beneficial for eg g producers and processors to use young (28-wk-old) and old birds (97- wk-old) for table egg production and birds of intermediate age (55- to 78-wk-old) for liquid egg production.