Changes in physical and chemical characteristics of turkey eggs throughout a laying cycle

The size and weight of the egg increases as turkey hens (flock) age throughout a laying cycle. The eggs laid during the first 5 wk (early-lay eggs) are generally smaller in size, have lower hatchability, and have lower posthatch survival rate of hatchlings. In contrast, mid-lay eggs (between wk 6 and 18) show higher hatchability and livability. For this project, increase in egg size was monitored throughout a production cycle, and physical (yolk, albumen, and shell weight) and chemical (protein, carbohydrate, energy, fat, and ash content) characteristics were compared between early-lay, mid-lay and late-lay periods. The increase in egg size and weight is not continuous, as several steps could be distinguished. Physical factors such as egg size, as well as volume and ratio of albumen and yolk, show significant changes between early-and mid-lay eggs. In addition, changes in energy level along with changes in moisture level were observed. In summary, because these differences can directly impact internal nutrient resources available and can affect hatchability and early posthatch performance, a proper incubation profile based on the age of the flock should be maximized to account for these differences and to promote the survival rate of embryos and consequently improve hatchability and livability of the hatchlings.