The chick hatching process is one of the most fascinating phenomena in poultry production. In just 21 days, a fertilized egg develops into a fully formed chick ready to survive outside the shell. Every stage of embryo development requires specific environmental conditions, and even small deviations in temperature, humidity, or ventilation can significantly affect hatchability and chick quality. In modern poultry hatcheries, the entire process is monitored by advanced control systems, making it possible to achieve hatchability rates exceeding 90% of fertile eggs.
Day 1–7 – The Beginning of Embryonic Development
Embryo development begins immediately after incubation starts. Within the first 24 hours, the circulatory system starts to form. During the first week, the most important body structures develop:
- the heart begins beating approximately 42 hours after incubation starts,
- the eyes begin to form,
- the brain develops,
- limb formation begins.
At this stage, embryos are particularly sensitive to temperature fluctuations. Studies show that prolonged exposure to temperatures below 37°C may increase embryonic mortality and negatively affect hatchability.
Day 8–14 – Intensive Organ Development
The second week of incubation is characterized by rapid growth and development. During this period, the following structures develop:
- the beak,
- claws,
- feathers,
- respiratory system,
- digestive system.
By day 14, the embryo occupies a significant portion of the egg’s internal space. Proper ventilation becomes increasingly important because embryos consume more oxygen and produce greater amounts of carbon dioxide. According to industry data, oxygen demand may increase several times compared to the first week of incubation.
Day 15–18 – Preparing for Hatching
During the third week of incubation, embryo development enters its final stage. The chick gradually assumes its characteristic hatching position:
- the head moves toward the air cell,
- the beak is positioned beneath the right wing,
- the body prepares for pulmonary respiration.
At this stage, the chick’s weight represents approximately 65–70% of the original egg weight. Around day 18, eggs are transferred from setter incubators to hatchers. Relative humidity is increased to approximately 65–70% to facilitate successful hatching.
Day 19–21 – Chick Hatching
This is the most spectacular phase of the entire incubation process. The chick first penetrates the air cell and begins breathing with its lungs. It then uses its egg tooth to gradually crack and break the shell. The process of emerging from the egg may take several hours.
A healthy chick should be:
- active,
- well hydrated,
- evenly feathered,
- free from developmental abnormalities,
- equipped with a properly healed navel.
The quality of day-old chicks is one of the most important indicators used to evaluate hatchery performance.
Which Factors Influence the Hatching Process?
Even a well-developed embryo may fail to hatch successfully if incubation conditions are not properly maintained. The most important factors include:
- temperature around 37.8°C,
- relative humidity of 50–60% during incubation and 65–70% during hatching,
- regular egg turning,
- proper ventilation,
- high-quality hatching eggs,
- effective biosecurity measures.
Industry analyses indicate that more than 60% of hatchability problems originate before incubation even begins, often during egg production, storage, or transportation.
Why Is Understanding Embryo Development Important?
A thorough understanding of embryo development helps poultry producers identify production issues more quickly and improve incubation performance more effectively. Each stage of development requires specific environmental conditions, which is why professional hatchery management involves not only monitoring technical parameters but also evaluating hatching egg quality, monitoring breeder flock health, and implementing effective biosecurity programs.
If you want to improve incubation results and increase the quality of day-old chicks, learn more about our professional poultry hatchery support services
