Eggshell temperature is key
LOOK-THINK-ACT
Which measurement is correct?
7 day weight (g)
ht
Chick yield (%)
pr ot
Effect of egg shell temperature on hatching results
ec
te
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Measure the eggshell temperature at the equator of the egg and not at the top, otherwise you will measure the temperature near the air cell. Air has an insulating effect, so you could measure a different value than the actual embryo temperature. If you do this manually, don’t wait too long to measure: after opening the door, the eggshell temperature will drop.
Because it is difficult to measure the embryo temperature, the eggshell temperature (EST) is measured. The EST differs approx. 0.1-0.2°C (0.20.4°F) from the embryo temperature, depending on the stage of incubation. At the start of incubation, when the eggs must be warmed, the embryo temperature is lower than the eggshell temperature. In a further stage of embryonic development, the embryo produces more heat and the embryo temperature will be higher than the EST. The heat that the embryo produces has to be removed. The same applies to the relationship between the eggshell temperature and the temperature in the incubator. Many other influences play a role, such as air velocity and evaporative heat. The eggshell temperature is therefore not the same as the air temperature in the incubator! In practice, each hatchery uses its own program. The eggshell temperatures affect the body weight and feed conversion rate of the day-old chick posthatch. The temperature in the incubator is often already reduced a long time prior to transfer of the eggs, otherwise the chick embryos could overheat between day 14 and day 18. At the end of the incubation period, the embryo temperature can exceed 40°C (104°F). And, at some locations, the variation in embryo temperature can increase by more than 2-3°C (4-5°F), depending on the position in the incubator, especially in places with little air movement and close to the spray nozzles.
99°F 37.2°C
99.5°F 37.5°C
100°F 100.5°F 101°F 101.5°F 37.8°C 38.0°C 38.3°C 38.6°C
py
98.5°F 36.9°C
rig
7 day mortality (%)
Eggshell temperature
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If the incubation temperatures are persistently too high or too low, there will be higher mortality in the first week and a lower chick weight after a week. The chick yield (chick weight/egg setting weight) is slightly higher at a lower incubation temperature, but within a week this positive effect has disappeared.
Which temperature measurement is corret? T=? T=? T=?
Heat production is highest towards the end of incubation. Any mistakes in temperature measurement must be avoided. After day 14, you should take a few temperature readings on each egg to avoid wrong measurements. Low temperatures may be caused by insufficient contact of the embryo with the eggshell; the highest reading is the correct value. The air cell is also getting larger and may have shifted a little to the left or right (incorrect turning angle?). 30
Maintain a constant embryo temperature of 37.8°C (100°F). Check the temperature using an infrared thermometer. Make sure the tip of the thermometer is flat against the equator of the egg.
Ha tc he ry S i gnal s
