The Effects of Age and Strain on the Relationships between Destructive and Non-Destructive Measurements of Eggshell Strength for White Leghorn Hens

Abstract

Specific gravity, egg and shell weight, compression fracture force (SBS), and non-destructive deformation (DFM) were measured and percent shell, surface area, and shell weight per unit surface area were calculated for a total of 3868 eggs obtained from four strains of Single Comb White Leghorns when the hens were 182, 315, 364, and 497 days of age. Strain and age influenced the measured and calculated variables with SBS and DFM showing the greatest differences. Analyses of variance showed that the y-intercepts and the slopes of linear regression equations of SBS on DFM were significantly affected by strain and age. Multiple regression analyses demonstrated that DFM most frequently accounted for the greatest portion of the variability in SBS. These results indicate that although non-destructive deformation is a useful predictor of shell breaking strength, the relationship is affected by strain and age of hen.