Incubation is the process of providing fertilised eggs with optimum conditions of temperature, relative humidity and ventilation necessary for the development of chicks and their successful hatching.
Types of Incubation
There are two types of incubation. These are:
1) Natural Incubation: The natural incubation is done by the hen itself, after having a number of eggs. The hen gets broody i.e ., it stops laying in order to incubate the eggs already laid. The hen lays up to 15 eggs and stops. It sits on the eggs and provides all conditions of temperature, relative humidity and ventilation required for the chicks to develop and hatch. It also turns its eggs on 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 realise 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.
2) Artificial Incubation: This is designed to provide the ideal conditions naturally provided by hen. It uses manmade devices called incubators to provide optimum conditions necessary for the development of the embryo into chick. The incubator is the most important equipment in hatchery. Many types of incubator, ranging in size from small to room type, are made. Eggs are set in trolleys.
Advantages of Artificial Incubation
- Hens do not have to stop egg production. Consequently, a large number of eggs are produced within a short period.
- 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 hen is between 41°C- 42°C. 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 18% 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.
Measures for the efficient operation of an egg incubator
- Maintain the right temperature during incubation.
- Test-run the incubator before you set eggs inside.
- Maintain the right RH during incubation.
- Allow for adequate escape of CO, from incubator.
- Ensure a regular power supply to the incubator
- Place incubator away from walls.
- Candle eggs progressively.
- Fumigate incubator before setting eggs.
- Incubator should be handled by trained and experienced personnel.
- Prior to setting eggs in the incubator, the eggs should be brought out from cold room and left to attain room temperature in order to eliminate sweating.
- 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.
- 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
- Temperature: Temperature is usually 37-39°C.
- 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.
- Ventilation (Air flow): 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%.
- 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.
- 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 automatic turning mechanism which turns the eggs six to eight times a day.
- Hatching: The 21-day incubation period of domestic fowl can be seen as consisting of first 18-19 days incubation in the setter and last two to three days hatching in the hatcher.
Testing for fertility: Infertile eggs and dead embryo can be detected about six 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 concentrated source of light through the egg in a dark room in order to see through the egg. It is usually not done in 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, live embryo shows a spider-like appearance in the egg. Infertile eggs are clear with no spider-like appearance.
During first candling, one can determine embryos that die during the first week called D1 (died within first week). These eggs do not show any radiating blood vessels. Rather, blood vessels adhering to the shell or a pink blood ring may be seen.
Second candling is done in the 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 the first and second period will be tested out, the live embryo nearly fills the egg or moves when the 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 ., D2.
Efforts to Ensure Uniformity of Hatching
The steps that should be taken to ensure that the eggs hatch at about the same time include the following:
- setting eggs uniformly on the tray,
- timely and regular turning of eggs.
- Ensure suitable environmental conditions, i.e, temperature, relative humidity and ventilation.
- proper candling of the eggs .,
- setting eggs at the same time.
- selecting eggs of the same size
- holding period for egg before setting should not be more than 14 days (2 weeks).
Operations Required After Hatching
Activities or operations normally carried out after hatching of eggs in the hatchery include:
- sexing of chicks into male and female.
- drying of chicks.
- Intra-ocular (I) NDV vaccinations.
- sorting out abnormal chicks.
- packing of normal and healthy chicks.
Breeding and Hatching: Fertilised eggs are incubated for 21 days using incubators, after which the eggs are hatched into young chicks. During the incubation period, adequate temperature, ventilation and relative humidity are maintained.
Incubators are made in varying sizes and designs. It uses different types of fuel (e.g. oil lamp, electricity, etc) to supply the heat required.
Function: Incubators are machines used for hatching fertilised eggs artificially. It takes 21 days for fertilised eggs of domestic fowl to develop and hatch in incubators.
Types of incubators include natural draught or table type and forced draught or cabinet type.
Conditions for Incubator to function
Before fertilised eggs are placed, the incubator should be run for 12-24 hours. For incubators to function properly, they require the following conditions:
- Temperature range of 37°C- 39°C.
- Relative humidity of 50 – 70%; an optimum level being 60%
- Adequate ventilation.
Components of an Incubator
An incubator is made up of a setter and a hatcher. The fertilised eggs are kept in the setter for 18 days while for the remaining three days before hatching, the eggs are placed in the hatcher.
The components of an incubator are:
- heat source e.g. lantern, heater or electric heater;
- control unit, damper or thermostat: it regulates the temperature of the incubator.
- heat distribution unit;
- relative humidity mediation unit which can be a basin of water, cotton-wool or humidifiers.
- felt tray – (to hold eggs and reduce cracking) or egg racks or egg trays;
- thermometer – to detect the degree of hotness or coldness of the machine;
- fan or air circulation unit or vent for ventilation;
- egg turning device for regular turning of eggs;
- insulator, to prevent heat loss.
Problems Associated with the Functioning of the Components
The problems that may lead to the malformation or non-functioning of the components of incubators include:
- If it is electrical incubator, power failure and irregular power supply would arise, but if it is kerosene-heat incubator, the problem that will arise include running out of kerosene.
- Thermostat: High or low voltage or current.
- Fan: Irregular power supply; over-heating through over-usage; loose nuts of the parts; improper lubrication of the movable parts.
- Thermometer: Problems include: cracking or breakage of the bulb/thermometer; loss of sensitivity.
- Ventilation: Blockage of vents.
- Water basin: Leakages; drying up of water contents.
- Insulator: Malfunctioning of the insulator unit.
- Turning device for egg tray: Lubrication of the movable joints or parts; loose nuts.
Efforts to Ensure Uniformity of Hatching of Eggs in Incubator
The steps that should be taken to ensure that eggs hatch at about the same time include:
- setting eggs uniformly in the tray;
- timely and regular turning of eggs;
- ensure suitable environmental condition such as ventilation and relative humidity;
- proper handling of the eggs;
- setting eggs at the same time;
- select eggs of the same sizes;
- holding period for eggs before setting should not be more than 14 days.
Operations Needed after the Hatching of Eggs in the Hatchery
Activities or operations normally carried out after hatching of eggs in the hatchery include:
- sexing of chicks;
- drying of chicks;
- intraocular (I) NDV vaccination;
- sorting out abnormal chicks;
- packing normal chicks.