Effect of egg weight on external and internal egg quality traits of Isa Brown egg layer chickens in Nigeria

This study was designed to determine the effect of egg weight on internal and external egg quality characteristics of Isa brown egg layer chickens. A total number of 105 eggs collected within 24 hours of lay were used for the study. Eggs were numbered, weighed and classified into three egg weight groups: Light (less than 49.99 g), medium (50 to 55 g) and heavy (greater than 55 g) egg weight groups. Data were collected on internal egg quality characteristics (yolk height, albumen height, albumen length, albumen width, Haugh unit, yolk index, albumen index and yolk diameter) and external egg quality characteristics (egg length, egg width, oblong circumference, egg shell weight, egg shape index and egg shell thickness). Data were analyzed using Statistical Package for the Social Sciences (SPSS) version 20.0. Egg weight had significant (P < 0.05) effect on egg length, egg width, oblong circumference, eggshell weight, and eggshell thickness. Egg weight did not significantly (P > 0.05) affect Haugh Unit, yolk index, albumen index, and albumen length of the three egg weight groups. However, significant differences (P < 0.05) were observed among the light, medium and heavy egg weight groups in terms of yolk height, yolk diameter, and albumen height and albumen width. Positive correlations (P < 0.05) were observed between egg weight and egg length, egg width, oblong circumference, eggshell weight and eggshell thickness. Egg weight also correlated positively (P < 0.05) with yolk height, yolk diameter, albumen height and width.