Relationship between egg-shell colour and two measurements of shell strength in the Vasca breed

Abstract

1. Egg-shell colour, egg specific gravity, shell thickness and egg weight were determined for 2080 eggs from three varieties of the Vasca, a Spanish brown-egg-laying hen.2. Intermediate, positive and significant (P < 0.01) correlation coefficients were found between egg-shell colour and specific gravity (0.25), or shell thickness (0.21). There was a very high (0.84), significant (P < 0.01) correlation between the measures of shell strength. 3. Shell thickness was accurately predicted with both specific gravity and egg weight as independent variables (determination coefficient 0.74); eggshell colour did not explain any further variation. 4. All traits showed considerable departure from normality in the form of negative kurtosis (shell colour and specific gravity), positive kurtosis (shell thickness and egg weight), negative skewness (shell thickness) or positive skewness (egg weight). 5. Egg-shell colour, specific gravity and shell thickness were less in July, in old birds and in eggs laid in the morning. Differences in egg quality traits between the three varieties were not significant.© 1984, British Poultry Science Ltd.