Effects of Age of Bird and Season of the Year on Egg Quality 1. Shell Quality

In these experiments, 2560 eggs from commercial laying hens were examined to determine the effects of age of bird and season of the year on selected egg shell quality characteristics. Shell thickness was significantly lower in the summer months. Specific gravity was significantly higher in the younger birds and during the cooler seasons. Age and season significantly affected shell weight and percentage of shell. Shell weight increased with increasing age of bird while percentage of shell decreased. During the spring and summer months both shell weight and percentage of shell decreased. Shell density was not significantly affected by age of bird but increased during the warmer months of the year. Shell weight per unit of egg surface area decreased during warmer months and no significant age effect was observed.