IncubationIncubation refers to the process by which birds hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period.The average incubation period for chickens is 21 days
TypesThere are two types of incubationNatural incubationArtificial incubation
Natural incubationIncubation under a broody hen is the ideal way to hatch a small number of eggs. A hen can successfully hatch 12-15 eggs depending on her size
Artificial incubationUse of a machine which warms, turns, humidifies bird eggs to incubate and eventually hatch them.
Requirement of incubationThese are the major requirement of incubationTemperatureHumidityVentilation/ airTurning
TemperatureTemperature is the most critical environmental concern during incubationDuring setter phase temperature required is 98.5-100.5F( 37.2-38.3C)During Hatcher phase temperature required is 98-99F (37-37.5C)
ContWhen incubation temperature deviate from the optimum level, hatchability will decline And the incidence of the malformed chicks will increaseToo high temperature results in excessive late embryonic mortalityLow setter temperature result in show embryo growth, late and uneven hatching, and high percentage of unhatched eggs.
Temperature requirement of different species
Species Temperature (C)Setter phaseHatcher phase Chicken 37.2-38.337-37.5Turkey 37.5 37.0 OGeese 37.737.5Duck 37.537.2Japanese quail37.5 37.1Pheasant 37.5 37.1Ostrich 36.1 36.736.0 - 36.7
HumidityHumidity is also important because the rate at which eggs lose water by evaporation depends on the ambient relative humidityThe relative humidity of air with in incubator should be about 60%During the last 3days the relative humidity should be nearer 65-70%
ContToo much moisture in incubator prevents normal evaporation and results in a decreased hatch, chick with a large yolk and a sluggish chick, which is difficult to saveToo little moisture result in excessive evaporation, causing chicks to stick to the shell, remain in the pipped shells, and sometimes hatch crippled
Chick with a large yolk
Humidity Requirement of different species
Species Humidity (%)Setter phaseHatcher phase Chicken 5565Turkey 5575Goose 50-55 75Duck 5565Japanese quail6070Pheasant 6590Ostrich 20 4060 70
Proper ventilation is important for successful incubationInsufficient ventilation may result in embryo or chick deathDuring the hatching period additional ventilation must be supplied to reduce the carbon dioxide in the incubatorEach process is speeded up approximately 100 times between the first and 21st day of incubation
VentilationSince 1,000 eggs require 143 ft3 of fresh air per day (oxygen in the air at 21%) on the 18th day of incubationAs the embryo grows it needs a larger supply of fresh air The movement of gases through the pores of the shell and the shell membranes is important because the developing embryo must receive a constant supply of oxygen and must eliminate carbon dioxide and moisture.
Oxygen in the Airoxygen content of the air in the setter and Hatcher remains at about 21%, but there may be some variation in the hatcher where large amounts of carbon dioxide are produced by the newly hatched chicksHatchability will drop about 5% for each 1% that the oxygen content of the air drops below 21%.
Gaseous exchange during incubationDay of incubationAbsorption of oxygen(ft3)Expulsion of carbon dioxide(ft3)10.500.2951.170.58103.791.921522.7011.501830.0015.402145.4023.00
Turning The turning process allows the embryo to revolve and slide in the inner white, yolk does not adhere to the shell membrane and provides access to additional nutrients for embryonic development.If turning is not occur in the incubator Deforming of the inner membrane started and eventually the yolk will touch the shell membrane
ContIf it happens embryo uppermost the embryo will stuck the shell and dieFor this reason turning is essential for the survival of healthy chickFor good hatchability, eggs should be turned to a position at least 45 from vertical, then reversed in the opposite direction to a similar positionEgg turning should be undertaken 6-8 times per day
ContEggs should not be turned in a complete circle, as this has a tendency to rupture the allantois sac with resultant embryonic mortality.Eggs should not be turned in either large or small incubators during the hatching period.
Referenceshttp://www.avianweb.com/images/products/brinsea/incubation.pdfJoseph M. Mauldin, Extension Poultry Scientist at the University of Georgia explains the exchange of oxygen, carbon dioxide and moisture in the egg during incubation in the Spetember 2003 issue of the University's Poultry TipsHandbook of poultry production (A Brief Encyclopedia)Commercial chicken meat and egg production 5th edition