Maintaining egg shell quality is important for maximizing production of broiler chicks from breeders as shell quality and hatchability go hand in hand. Thin shells allow for higher water vapor loss during incubation resulting in dehydrated chicks and higher late embryonic mortality.
Also, egg shells that are thin crack easily during collection and transportation, resulting in poor hatches and higher losses of chicks, from both contamination and excessive moisture loss. The major factors that influence egg shell quality are genetics, diet, climate, housing and age of the hens. Therefore, current knowledge of a flock’s shell quality allows for better management of that flock by changing management practices to improve poor quality egg shells and subsequent hatchability and chick quality.
Of the different measures of egg shell quality, egg specific gravity is the easiest and most widely utilized method. Specific gravity is used to measure shell thickness and, indirectly, the percentage of shell deposited on the egg. There are two methods to obtain egg specific gravity, the Archimedes method and the salt solution method. The Archimedes method involves weighing eggs individually, then weighing them in water and then using the formula; [dry weight/(dry weight-wet weight)]. The salt bath method utilizes several tubs of salt water containing graduated levels of salt solution.