Factors Influencing Shell Quality of Aging Hens

Abstract

Two experiments were conducted in which eggs were collected from hens of different ages or from individually caged hens during their first 10 months of lay. Shell weight, egg weight, specific gravity, egg production, and shell thickness were the criteria evaluated. Results indicated that the total amount of shell deposited on the egg at 3-months of lay did not decrease but remained fairly constant or increased slightly throughout the remainder of the laying period. However, the increase in egg weight with no proportionate increase in shell deposition resulted in a decline in shell quality (shell thickness and specific gravity). Eggs which had the greater increase in size throughout lay had the greater decline in shell quality. Neither the number of eggs laid by the hen nor absolute egg size had any influence on shell quality. However, shell quality at the end of lay was directly related to shell quality at the beginning of lay.