Incubation is the process of providing fertilized eggs with optimum conditions of temperature, relative humidity and ventilation necessary for the development of chicks and their successful itching.


There are two types of incubation. These are:
Natural and artificial incubation

Natural Incubation:

The natural incubation is done by the hen itself, after having a number of eggs. The hen broody i.e., it stops laying in order incubate the eggs already laid.

The hen lays up to 15 eggs and stops. It sits on the e 4 and provides all conditions of temperature relative humidity and ventilation required for the chicks to develop and hatch.

It turns its eggs on a regular basis. This practice is common in the villages where chickens are raised extensively and places where there are no facilities for artificial incubation.

Natural incubation is not desirable in commercial poultry production because, when hens go broody, egg production stops i.e. the commercial enterprise will not realize a good number of eggs from its flock.

The number of eggs that can be incubated by a hen at any time is very small.
Storage: The body temperature of the hen is between 41’C- 42C. At the time the egg is

Artificial Incubation:

This is designed to provide the ideal conditions naturally provided by hens. It uses man-made devices called incubators to provide optimum conditions necessary for the development of the embryo into the chick.

The incubator is the most important piece of equipment in hatchery. Many types of incubators, ranging in size from small to room type, are made. Eggs are set in trolleys.


1. Hens do not have to stop egg production. Consequently, a large number of eggs are produced within a short period.
2. Large number of eggs are incubated and hatched at the same time (incubators of over 100,000 egg capacity are even available)

Collection and Storage of Hatching Eggs

Collection: Hatching eggs are supposed to be collected at least 3- 4 times a day. Under our tropical environment, it is good to collect more often than this.

This will help to reduce deterioration and consequently reduce hatching potentials.

Storage: The body temperature of the hen is between 41oc – 42oC. At the time the egg is dropped, it is at that body temperature and the embryonic development still continues.

This reduces the hatching potential of the egg. Consequently, eggs are stored in egg holding room for periods ranging from two days to two weeks.

Storage conditions include a temperature of about 1 8 and a relative humidity of 75 -80 %. Eggs are stored with the large end facing upward while turning of the eggs may not be necessary within the first two weeks but above two weeks.

Turning is advisable to prevent contact of embryos with shell membrane, which may cause dehydration or physical damage.



(i) Maintain the right temperature during incubation
(ii) Test-run the incubator before you set eggs inside
(iii) Maintain the right RH during incubation
(iv) Allow for adequate escape of CO, from incubator

(v) Ensure a regular power supply to the incubator
(vi) Place incubator away from walls
(vii) Candle eggs progressively
(viii) Fumigate the incubator before setting eggs
(ix) Incubator should be handled by trained and experience personnel

Incubation Procedures

(1) Prior to setting eggs in the incubators the eggs should be brought out from the cold room and left to attain random temperature in order to eliminate sweating.

(ii) The incubator which must have been cleaned and disinfected if started early enough, to attain optimum temperature and relative humidity before eggs are placed in it.

(iii) The eggs are arranged in egg-setting trays and placed in the incubator. It is good practice to fumigate the eggs before setting.

Optimum Incubation Conditions

(i) Temperature: Temperature is usually37-39°C.
(ii) Relative humidity: Relative humidity of 50 – 60% during the first 19 days and 75% during the last two to three days to prevent dehydrating the chicks in the hatcher.

(iii) Ventilation (Airflow): Free movement of oxygen, nitrogen, carbon dioxide and water vapour through the shell is very essential for the developing embryo. The tolerant limit of carbon dioxide in incubator or hatcher is 0.5%.

(iv) Egg Positioning during Incubation: Eggs are usually placed in the incubator with the large end facing upward. However, some studies indicate that eggs set with the large ends downward hatch equally good and under natural conditions, the hens hatch eggs in horizontal position.

(v) Egg Turning: If eggs are left in one position throughout the incubation period, they hatch poorly. This is because of physical damage caused by the yolk sticking to one side of the shell. Under natural conditions.

the hen turns the eggs with her beak and body. However, modern incubators are also equipped with an automatic turning mechanism which turns the eggs six to eight times a day.

Hatching process using the incubator

The 21-day incubation period of domestic fowl can be seen as consisting of the first 18-19 days of incubation in the setter and the last two to three days of hatching in t
Hatching Operation
(i) Testing for fertility: Infertile egg and dead embryo can be detected about days after incubation by the process called candling.

The machine used to detect living or dead and developing embryos is called the egg candler. Candling consists of the passage of a concentrated source of light through the egg in a dark room in order to see through the egg.

It is usually not done on a commercial basis because of the number of eggs involved. However, it is routinely done in research stations.

At least two candling are done usually in six to seven days of incubation. With candling, you can determine fertile eggs.

Here, a live embryo shows a spider-like appearance in the egg. Infertile eggs are clear with no spider-like appearance.

During the first candling, one can determine embryos that die during the first week called Dl (died within the first week).

These eggs do not show any radiating blood vessels. Rather, blood vessels adhering to the shell or a pink blood ring maybe seen.

Second candling is done in e 18/19 day prior to transfer of, the eggs from setter to the hatcher for hatching.

If the first candling was well done, only dead embryos in the period between he first and second period will be tested put ,tie 1ie embryo nar1y fills the egg or moves when tie egg is rotated and blood vessels become apparent.

Dead embryos appear as a liveless mass of dark shadow. During the second candling, the live embryo fills the entire egg, i.e., D.


The steps that should be taken to ensure that the eggs hatch at about the same time include the following:
(i) setting eggs uniformly on the tray
(ii) timely and regular turning of eggs

(iii) ensure suitable environmental conditions, i.e temperature, relative humidity and ventilation
(iv) proper candling of the eggs
(v) setting eggs at the same time

(vi) selecting eggs of the same size
(vii) holding period for the egg before setting should not be more than 14 days (2 weeks)


Activities or operations normally carried out after hatching of eggs in the hatchery include:
(i) sexing of chicks into male and female
(ii) drying of chicks
(iii) intra-ocular (I) NDV vaccinations
(iv) sorting out abnormal chicks
(v) packing of normal and healthy chicks


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