Incubation is the management of fertilized eggs to ensure the normal development of the embryo into a normal chick. Incubation can be achieved naturally (when the hen sits on the eggs for a period of time and keeps the eggs warm until hatching) or artificially by using machines known as incubators which provide the necessary heat until hatching.
Some essential requirements of incubation include temperature, humidity, turning of the eggs, candling, etc.
Reproductive System of Hen
The left ovary produces numerous ova. Mature ova are released into the infundibulum where fertilization takes place.
The ovum then migrates down to the magnum where it receives its albumen, then to the isthmus where the shell membranes, some albumen, water, and mineral salts are added. The shell is formed in the uterus for 18-21 hours.
From ovulation to laying takes 24-26 hours.
The avian egg
The avian egg is described as irregular ovoid and it is divided into three main parts
Composition of the egg
| Nutrients | Yolk | Albumen | Shell |
| Water | 48 | 86 | 2 |
| Protein | 17 | 12 | 5 |
| Fat | 33 | 12 | – |
| Ash | 1 | 1 | 93 |
| Carbohydrate | 1 | 1 | – |
Read Also: Causes of Egg Production Reduction in Poultry Farms and Ways to prevent them
Factors Affecting Egg size
Genetic factors
Age of the birds
The protein level of the diet
Environmental factors
Size of the birds
Ovum size
The intensity of egg-laying
Sex Separation
The early separation of the sex of young chicks is an important economic factor. There are several ways of sexing chicks.
By manual vent inspection at day old. At the center of the vent of a male chick is located a pin edge size structure called the process. This can be easily seen with aid of the magnifying lens. A female vent shows no such structure.
Sexing can also be done when the chicks are five to eight weeks old. Such a separation is based on larger size combs and wattles, longer tail feathers, stouter shanks, with prominent scales, and generally larger body size in cockerels than in pullets.
Sex-linked color differentiations: for example at day old, the golden comet breed has dark gold colored pullets while the cockerels look white.
In conclusion, the avian egg, therefore, can be divided into three main parts shell and shell membranes, albumen and chalazae, and the yolk.
The egg can be incubated either naturally or artificially. Hatchability, as well as fertility, is affected by genetic factors but again it is management that goes above genetics in its effect.
Factors affecting egg size include; genetic factors, age of the birds, the protein level of the diet, environmental factors, size of the birds, ovum size, and intensity of laying.
The essential requirements of artificial incubation are adequate ventilation, relative humidity of 60-65%, a temperature of 37.5˚C, and turning at least three times daily.
The incubator operation is divided into the setting and the hatching phase.
Hatchability refers to the percentage of eggs that were hatched; it should be about 80-90% from a good flock.
Factors affecting hatchability are fertility, genetics, nutrition, diseases, egg selection, and management practices.
