Incubation is the process of aiding the development of a fertilized egg into a life chick by providing such factors as adequate temperature, humidity, ventilation, and turning.
There are two methods of incubation; Natural incubation and Artificial incubation.
Natural incubation: That is getting the hen to sit on fertilizing the egg to incubate the egg.
Artificial incubation: Artificial incubation is carried out with an incubator using fuels such as kerosene, gas, coal, etc.
Essential Requirements of Artificial Incubation
Adequate ventilation- there should be sufficient oxygen to supply the respiratory need of the embryo. Also, carbon dioxide resulting from embryonic metabolism should not be allowed to accumulate.
Relative humidity of 60-65% should be provided to prevent excessive water loss by the egg.
An adequate temperature should be provided to ensure that life within the egg is maintained at the optimum level. The temperature of 37.5◦C is ideal.
Turner: There should be a turner to prevent the embryo from getting a stuck shell. This should be done at least three times daily.
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Operation of the Incubator
This is divided into two phases;
The setting of the eggs is 0-18 days.
Hatching of the eggs 19-21 days.
Some incubators combine the two operations while others are separate. The selected eggs are set on trays with the large ends up and placed in the incubator.
The temperature requirement during the first week is 38oC, 39oC for the second week, and 40oC for the third week.
The relative humidity requirement is 60-65%. There should also be free passage of air in the incubator. The egg should be turned at least three times daily up to the 18th day. On the seventh and sixteenth days of incubation, the eggs are checked for infertile eggs and dead embryos by candling.
Candling is the process of testing incubated eggs for the fertility and development of the embryo. This is done by holding the egg before a strong shaded light see fig 4.4 or placing a strong hand torch under the tray.
Hatching
The eggs are moved from the incubator to the hatching compartment for 18 days. The eggs are laid (Placed) flat in preparation for hatching. The relative humidity should be higher (70%) in the hatching compartment.
Hatchability
Hatchability refers to the percentage of eggs that were hatched, it should be about 80-90% from a good flock
Hatch of Fertile
This refers to the percentage of fertile eggs that were hatched.
Hatch of Total
This refers to the percentage of total eggs that were hatched.
Example: supposing 500eggs were incubated, after 7 days. 450 were found to be fertile. If 400 of the fertile eggs hatched into chicks. Calculate the hatch of fertile and the hatch of the total.
Solution: Total eggs = 500
Fertile eggs = 450 Hatched eggs = 400
%hatch of fertile = 400/450 x 100 = 88.89%
% hatch total = 400/500 x 100 =80.0%
Note:
The Hatch of Fertile is usually higher than the hatch of the total.
Hatch of fertile is more precise because fertility is considered.
Hatch of Fertile is of practical importance as it refers to the performance of the breeder stock.
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.
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