Shell Evaluation of White and Brown Egg Strains by Deformation, Breaking Strength, Shell Thickness and Specific Gravity

Abstract

Phenotypic correlations were calculated between measures of egg shell strength obtained by non-destructive deformation, breaking strength, shell thickness and specific gravity of five commercial white and brown egg strains. Correlations between values obtained by all methods were highly significant for all strains. Correlations between the strength measurements and the egg characteristics of width/length ratio, egg weight and tint of the shell between the strains were also determined. The correlations between the tint of brown shells with all methods of evaluating shell quality were not significant. Although the shell thickness, specific gravity and shell deformation values of the brown egg strains were poorer than that of the white egg strains, the breaking strength of shells from brown egg strains was higher. This indicates that thinner shells are not necessarily weaker and suggests caution against drawing conclusions from only one method of assessing shell strength. Coefficients of variation were larger for shell deformation and breaking strength measurements than for shell thickness and specific gravity. Shape (width/length ratio) and egg weight showed little correlation with any methods of assessing shell strength.

Shell Evaluation of White and Brown Egg Strains by Deformation, Breaking Strength, Shell Thickness and Specific Gravity

“…Snapir, 1970) determined which egg characteristics contributed the most variation to egg shell strength or quality measurements. Significant correlations between the shell strength measurements of deformation (nondestructive) and breaking strength (destructive) with the egg characteristics of shell thickness and specific gravity were reported by Potts and Washburn (1974). This work reported high statistical correlations between the two strength measurements but did not indicate which shell characteristics accounted for the most variation in either of the shell strength measurements.…”

“…They could explain the observation that brown eggs may have thinner shells than white eggs but may break less readily (Hunton, 1969). Potts and Washburn (1974) reported that although brown eggs had a lower specific gravity, shell thickness and deformation, their breaking strength was superior to comparable white eggs. Table 4 illustrates the relative differences in sources of variation of breaking strength.…”

“…Although differences between brown and white eggs have been emphasized, there are also differences between the strains of either the white egg or brown egg layers (Potts and Washburn, 1974).…”

“…This work reported high statistical correlations between the two strength measurements but did not indicate which shell characteristics accounted for the most variation in either of the shell strength measurements. Potts and Washburn (1974) also reported differences in brown and white egg strains in the measurements of shell thickness, specific gravity, deformation and breaking strength.…”

Qualidade dos ovos de poedeiras comerciais alimentadas com levedura seca de cana-de-açúcar

“…A partir das cascas secadas ao ar, foi obtido o peso da casca (PC), utilizando-se balança com aproximação de 0,01 g. A espessura da casca (EC) foi determinada conforme Tyler (1961), Potts & Washburn (1974) e Nordstrom & Ousterhout (1982). Quatro pedaços da casca seca com membrana foram retirados da região equatorial do ovo.…”