A chicken’s entire egg-laying cycle, from ovulation to shell formation, takes approximately 24 to 26 hours. Hens typically begin laying their first eggs around 18 to 24 weeks of age, though this varies by breed. After the first “pullet” eggs, size gradually increases, and peak production occurs during the first laying year, after which production declines.
The egg-laying cycle (internal process)
- Ovulation: A yolk is released from the ovary and enters the oviduct.
- White formation: The albumen, or egg white, begins to form around the yolk.
- Shell membrane formation: The yolk and white are encased in a double membrane.
- Shell creation: The egg enters the uterus, where the shell is formed.
- Pigment & bloom: For colored eggs, pigment is applied during this stage. A protective coating called the bloom or cuticle is also added before the egg is laid.
The laying timeline
Start of laying: Most commercial chicken breeds (e.g., ISA Brown, Lohmann Brown) begin laying small “pullet eggs” around 18–22 weeks of age.
Egg size increase: Eggs grow from small to medium within about a week and reach full size within two weeks.
Peak laying phase: Hens achieve their highest production rates (90-95%) in well-managed flocks between 18 and 35 weeks of age.
Decline & molting: Production gradually decreases after about 35–40 weeks of age.
Annual production: A hen’s prime laying cycle can last a little over a year, with production slowing afterward.
Factors influencing egg-laying
Breed: Different breeds have different maturity rates and laying patterns.
Age: Younger hens in their prime are more productive than older hens.
Nutrition and management: Proper feeding and care are crucial for consistent egg production.
Environment: Factors like light, temperature, and stress can influence a hen’s productivity.
