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Embryonic development continues if fertile eggs are maintained above 20°C. Therefore, it is
essential to collect eggs frequently and store them under cool conditions.
Eggs should be collected at least twice daily, and preferably three or four times. For best
hatchability, eggs should be stored no longer than a week before setting.
The best temperature for storing hatching eggs is 10 to 16°C. Storage humidity is also im-
portant. Humidity below 70 per cent causes the eggs to lose excessive moisture. Below are the
correct wet-bulb readings for a given humidity at the storage temperature. If you do not have a
specific cool room, store the eggs in a cool, dry place. Eggs stored under conditions where the
temperature and humidity vary tend to start and stop incubation, resulting in pre-incubation
and lower hatchability.
Wet-bulb reading
Dry bulb
60% relative humidity
°C
°C
10
6.8
11.1
7.6
12.2
8.4
13.3
9.6
14.3
10.7
15.3
11.5
Other factors affecting success
Rough or careless handling when transferring eggs to the hatching compartment or prolonged
delays during transfer, resulting in chilling, may cause embryo deaths.
Excessive inbreeding of poultry may result in lethal or semi-lethal genes, which also cause
mortality during incubation.
Consistent temperature
A hen's normal body temperature varies between 40.5 and 41.7
her degree of activity at the time. The optimum temperature at the centre of an incubated egg
is approximately 37.8
may reach 39.2 to 39.4
In modern fan-forced incubators, the manufacturer's recommended temperature setting is be-
tween 37.5 and 37.64
movement in this type of incubator keeps the eggs' temperature the same as the incubator's.
An embryo's heat production increases as incubation progresses. The temperature increase is
greatest during the last two days due to embryo activity. Egg temperature rises up to 2
above the incubator's ambient air temperature, which is why the temperature is often lowered
o
by up to 1
C.
Incubation faults and causes checklist
How to locate and rectify faults in incubation technique
#
Problem
Probable causes
(a) Wrong proportion of males to
Too many
1
females
© by WilTec Wildanger Technik GmbH
http://www.wiltec.info
o
C. When hatching under a broody hen, the upper surface of the egg
o
C but the egg's centre will not exceed 37.8°C.
o
C. The lethal temperature for eggs is 39.4
70% relative humidity
°C
7.4
8.3
9.4
10.6
11.5
12.2
o
C, depending on the bird and
o
C. The constant and rapid air
Action
(a) Check mating ratios according to
breeder's recommendations
80% relative humidity
°C
8.2
9.3
10.5
11.4
12.1
13.3
o
C
Seite 9
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