Interrelationships between shell quality and egg production and egg and shell weights in white leghorn and white rock hens

Abstract

Synopsis Interrelationships between shell quality, production rate, egg and shell weights in relation to seasonal changes were compared in White Leghorn (WL) and White Rock (WR) hens. An increase in the average egg weight was observed in both breeds during the hot summer months. The weight and quality of the shell decreased gradually in eggs laid by WL hens, but increased in those from WR during the summer. Significant negative correlation coefficients were found between shell quality and egg weight in only the WL, when analysed on the basis of individual averages for the entire experimental period and on weekly averages for the breed. No significant correlation was found between shell quality and production rate in WL hens. Great variabilities were obtained between individual birds regarding the correlations between shell quality and egg weight and between shell quality and production rate, when calculated on the basis of seasonal changes in both breeds. Multivariate analysis, in which shell quality was ...