The porous character of the shell allows water to evaporate from the egg. Hens receiving insufficient amount of Vitamin D have thinner shells. The uterus give the definite form to the egg. Blunt to tapered end . The uterus has the strongest muscle and determines the shape of the egg.
Production is composed of cycles, production, decreased production, or entire cessation.
Each cycle composed of litters. A litter consisting of a period of continuous production with out break. Each litter composed of clutches , clutch is continuous production successive days with eggs on either end of the litter being smaller than those in the middle of litter. With the amount of ration and water fed the hens having great effect on egg weight. Also the 2nd egg of a 2 egg clutch is smaller than the first egg.