Small Flock Factsheet, Number 8
Phillip J. Clauer, Poultry Extension Specialist
Animal & Poultry Sciences Department
Introduction
Percent Fertility is the percentage of fertile eggs
of all eggs
produced.
Percent Hatchability is the percentage of fertile
eggs which
actually hatch out as live young.
Care of Hatching Eggs
Before setting eggs in an incubator, you must obtain or
produce
quality fertile eggs from a well-managed,
healthy flock which are fed properly balanced diets.
Be sure eggs are dry before storing. Never place damp or
wet
eggs in a styrofoam carton for storage.
Slant or turn the fertile eggs daily while they are being
stored. Store the eggs small end down and slanted
at 30-45 degrees. Putting a piece of 2" x 4" under one end
of
the carton or storage container and changing
it to the other end daily works well.
Do not store eggs for more than 10-14 days. After 14 days
of
storage, hatchability begins to decline
significantly.
Incubation
Four factors are of major importance in incubating eggs
artificially: temperature, humidity, ventilation and
turning. Of these factors, temperature is the most
critical.
However, humidity tends to be overlooked and
causes many hatching problems. Extensive research has shown
that the optimum incubator temperature is
100°F when relative humidity is 60 percent.
Concentrations
of
oxygen should be above 20 percent, carbon
dioxide should be below 0.5 percent, and air movement past
the
egg should be 12 cubic feet per minute.
There are two types of incubators commonly used:
The forced-air incubator should be set at 99-99.5°F and
60-65%
relative humidity (83-88°F wet bulb). The
advantage of the forced-air incubator is that it is easier
to
maintain humidity at a constant level because of
air circulation.
Still air incubators are smaller and air flow is harder to
manage. Set still-air incubators at 100 to 101°F at
egg
height. This is important since the air stratifies in these
incubators. There can be as much as a 5° difference
in temperature from the top to the bottom of some of the
still-air incubators. Humidity should be 60-65%
(80-90° wet bulb) during incubation and 70-75% (92-97° wet
bulb)
at hatching time. It is very easy to overheat
the eggs in still-air incubators and difficult to maintain
proper humidity.
Temperature
During the warm-up period, the temperature should be
adjusted to
hold a constant 101°F for still air, 99°-
100°F for forced air. To obtain reliable readings, the
bulb
of
the thermometer should be at the same height
as the tops of the eggs and away from the source of heat.
Using
two thermometers is a good idea to ensure
you are getting an accurate reading.
Incubator temperature should be maintained between 99° and
100°F. The acceptable range is 97° to 102°F.
Mortality is seen if the temperature drops below 96°F
or
rises
above 103°F for a number of hours. If the
temperature stays at either extreme for several days, the
eggs
may not hatch. Overheating is more critical than
underheating. Running the incubator at 105°F for 15
minutes
will seriously affect the embryos, while running
it at 95° for 3 or 4 hours will only slow the chick's
metabolic
rate.
An incubator should be operated in a location free from
drafts
and direct sunlight. An incubator should also
be operated for several hours with water placed in a pan to
stabilize its internal atmosphere before fertile eggs
are set. Do not adjust the heat upward during the first 48
hours after eggs are set. This practice cooks many
eggs. The eggs will take time to warm to incubator
temperature
and many times in small incubators the
incubator temperature will drop below 98°F for the
first 6-8
hours or until the egg warms to 99°-100°F.
In Case of Power Outage
If you experience a power failure, do not scrap the hatch.
Most
of the time the hatch can be saved. The key
is to keep the eggs as warm as possible until the power
returns.
This can be done by placing a large cardboard box or
blankets
over the top of small incubators for additional
insulation. To warm the eggs, place candles in jars, light
them
and place the jars under the box that covers
the incubator. Be careful not to put any flammable material
closer than a foot from the top of the candles.
The heat from the candles can easily keep the eggs above
90°F
until the power returns.
Embryos have survived at temperatures below 90°F for up
to
18
hours. You should continue to incubate the
eggs after the outage; then candle them 4 to 6 days later to
check for further development or signs of life.
If, after 6 days, you do not see life or development in any
of
the eggs, then terminate incubation. Most of the
time, a power outage will delay hatching by a few days and
decrease the hatchability to 40-50 percent.
Humidity
The relative humidity of the air within an incubator should
be
about 60 percent. During the last 3 days (the
hatching period) the relative humidity should be nearer
65-70
percent. (Too much moisture in the incubator
prevents normal evaporation and results in a decreased
hatch,
but excessive moisture is seldom a problem in
small incubators.) Too little moisture results in excessive
evaporation, causing chicks to stick to the shell,
remain in the pipped shells, and sometimes hatch crippled.
The relative humidity in the incubator can also be varied by
changing the size of the water pan or by putting
a sponge in the pan to increase the evaporative surface.
The
pan should be checked regularly while the
incubator is in use to be sure that there is always an
adequate
amount of water. Adding additional water pans
to small still-air incubators is also helpful to increase
humidity.
During the hatching period, the humidity in the incubator
may be
increased by using an atomizer to spray a
small amount of water into the ventilating holes. (This is
especially helpful when duck or goose eggs are
hatching.)
Whenever you add water to an incubator, it should be about
the
same temperature as the incubator so you
do not stress the eggs or the incubator. A good test is to
add
water just warm to the touch.
Using a wet-bulb thermometer is also a good way for
determining
relative humidity. The wet-bulb
thermometer measures the evaporative cooling effect. If the
wet
and dry bulb read the same temperature, you
would have 100 percent humidity. The greater the
evaporation
taking place, the lower the temperature reading
on the wet-bulb thermometer and the larger the spread will
be
between the wet- and dry-bulb readings.
To make a wet-bulb thermometer, just add a cotton wick to
the
end of a thermometer. Then place the tail
of the wick in water. The cotton then absorbs the water.
As
the water evaporates from the cotton it causes
a cooling effect on the thermometer.
The table below (Relative Humidity) will enable you to
calculate
relative humidity using readings from a wet-
bulb thermometer and the incubator thermometer.
Ventilation
The best hatching results are obtained with normal
atmospheric
air, which usually contains 20-21 percent
oxygen. It is difficult to provide too much oxygen, but a
deficiency is possible. Make sure that the ventilation
holes are adjusted to allow a normal exchange of air.
This is critical on home-made incubators. It is possible to
suffocate the eggs and chicks in an air-tight
container. However, excessive ventilation removes humidity
and
makes it difficult to heat incubators properly.
Turning
Eggs set on their sides must be rotated 1/2 turn at least 3
times daily. Eggs set with the air cell end up should
be tilted in the opposite direction 3 times daily. This
keeps
the embryo centered in the egg and prevents it
from sticking to the shell membrane. If hand turning, to
insure
proper turning, mark each side of the egg with
a pencil. Put an "x" on one side and an "o" on the opposite
side.
Stop turning the eggs for the last three (3) days of the
incubation cycle (at 18 days for chickens, 25 days for
waterfowl, etc.) and do not open the incubator until the
hatch
is completed to insure that a desirable hatching
humidity is maintained.
Hatch Time
Do not help the chicks from the shell at hatching time. If
it
doesn't hatch, there is usually a good reason.
Also, prematurely helping the chick hatch could cripple or
infect the chick. Humidity is critical at hatching
time. Don't allow your curiosity to damage your hatch.
As soon as the chicks are dry and fluffy or 6 to 12 hours
after
hatching, remove the chicks from the incubator.
It is good practice to remove all the chicks at once and
destroy
any late hatching eggs. Hatching time can be
hereditary and you can control the uniformity of hatching by
culling late hatchers. If you keep every chick
which hatches late, in a few years each hatch could last 4
days
or longer.
Sanitation of Incubator and Equipment
No matter what type of incubation you use, it is important
that
you thoroughly clean and disinfect the
incubator before and after you use it. It is just as
important
that the incubation room and egg storage area
are kept equally clean. The lack of sanitation will
decrease
hatchability.
Immediately after each hatch, thoroughly clean and disinfect
all
hatching trays, water pans and the floor of the
hatcher. Scrape off all egg shells and adhering dirt. Wipe
clean surfaces thoroughly with a cloth dampened
in quaternary ammonium, chlorox or other disinfectant
solution.
Incubation Periods of Other Species
One of the miracles of nature is the transformation of the
egg
into the chick. In a brief three weeks of
incubation, a fully developed chick grows from a single cell
and
emerges from a seemingly lifeless egg.
Visit
Virginia Cooperative Extension.
Introduction
Many domestic bird owners incubate eggs to help sustain
their
flock over time. This fact sheet is designed to
assist those who wish to incubate small numbers of domestic
poultry eggs.
The words "fertility" and "hatchability" are often used
incorrectly by small producers. These terms are
important and have very important meaning.
(From Egg to Chick, Northeast State Cooperative Extension
Service)
Incubator Temperature
Wet Bulb Readings
100°F
101°F
102°F
81.3
82.2
83.0
83.3
84.2
85.0
85.3
86.2
87.0
87.3
88.2
89.0
89.0
90.0
91.0
90.7
91.7
92.7
Percent Relative
Humidity
45%
50%
55%
60%
65%
70%
Incubation Periods (species and days required
to hatch)
Bobwhite Quail
Chicken
Chukar Partridge
Coturnix Quail
Ducks
Geese
(23-24)
(21)
(23-24)
(16-18)
(28)
(28-33)
Guinea
Muscovy Duck
Pheasants
Ostrich
Swan
Turkey
(27-28)
(35)
(24-26)
(42)
(35)
(28)