- Artificial incubation is commonly used in aviculture. Eggs incubated in this way
are safe from predation and are not at risk of being deserted by the bird sitting on them,
for example due to disturbance. Eggs in incubators are at risk if the power supply to the
incubator fails, for example if there is an electrical power cut.
- Artificial incubation allows many more eggs to be incubated than parent
incubation and with less effort than maintaining broodies. However, very precise control
and attention to the progress of individual eggs is required for the best results.
- Accurate control of temperature and humidity are vitally important in artificial
incubation. Cleanliness is also very important; the ease with which an incubator may be
cleaned and disinfected is an important consideration when choosing an incubator.
- The area in which incubators are kept should be easily cleaned and well
ventilated, and should also be maintained at a constant temperature.
- Most modern incubators are electric, although paraffin and gas powered incubators
do still exist. Incubators vary greatly in size, may be still air (in which air moves by
convection) or forced air (in which air is moved using a fan) and may or may not include
automatic egg turning.
- All incubators also require added water to maintain the correct humidity. This is
usually provided in the form of one or more water trays.
- Still air incubators, which have a temperature gradient from the top (higher
temperature) to the bottom of the incubator may approximate the natural conditions in a
nest (in which the incubating parent is providing heat from above), but they may easily be
overloaded and the eggs then poorly ventilated. Forced air incubators have a much more
uniform temperature throughout, and better ventilation, and may be used for many more
- N.B. Individual preference plays a large part in choosing an
incubator. In general, better results are likely to be obtained if the operator is
familiar with, and comfortable using, the incubator.
- Incubators should be cleaned and disinfected (and fumigated if required - see: Formaldehyde Fumigation of
Incubators) before the breeding season. A disinfectant suitable for
incubators should be chosen and care is needed in cleaning the Once clean, they
should be set up without any eggs and switched on.
- After the incubator has warmed up and appears to be at the correct operating
temperature, it may be tested by incubating some bantam eggs. The temperature should be
monitored and recorded several times daily, but adjusted on the basis of average daily
readings rather than by micro-correction every few hours.
- Wet-bulb readings should also be monitored to indicate humidity levels. A pattern
of a slight rise in readings on the wet-bulb thermometer may indicate a soiled wick and
this should be changed (B42).
- For ideal results, all the eggs inside one incubator should be of the same age
(stage of incubation) and size. In practice, eggs of different sizes and ages are commonly
incubated in the same machine.
- Eggs close to the end of incubation produce a considerable amount of heat and
therefore contribute locally to the air temperature, particularly in a still-air
- Large late-incubation eggs should not be placed near to small, newly-set eggs as
they may affect their incubation temperature.
- Incubators are most reliable if kept in a room with a constant temperature.
Maintaining a steady incubator temperature inside a room which varies widely in
temperature is practically impossible.
- The temperature inside an incubator should be measured with a thermometer. This
may be either a traditional mercury thermometer or an electronic thermometer. The bulb of
the thermometer may be placed inside a blob of Plasticine or similar to reduce changes in
readings due to minor fluctuations and give an average reading. It is important to make
sure that the readings on the thermometer are accurate or, if there is an error, that the
error is known, stable and can be corrected for. New thermometers should be checked
against one known to be accurate. Either traditional mercury thermometers or digital
thermometers may be used.
- Even in a forced air incubator there will be differences in temperature within an
incubator, which may be mapped by placing thermometers in different places within the
incubator. In a still air incubator the temperature varies vertically within the incubator
and there may be a difference of several degrees between the bottom and the top of the
incubator. The temperature should be kept at that required by the eggs at the
level at which the eggs are kept. In order to monitor this, a thermometer should be
placed at the same level as the eggs.
- N.B. the temperature will fall when the door is opened to add,
remove or manipulate eggs. These procedures should be carried out quickly but carefully.
- For normal development, eggs must be maintained within a narrow
temperature range. Both too high and too low temperatures may be deleterious to
eggs, although in general eggs are more tolerant of low than high temperatures:
- Incorrect temperatures affect incubation time, with earlier hatching if the
temperature has been slightly high, later hatching if the temperature has been slightly
- Temporary cooling (as may occur naturally when an incubating bird leaves the nest
to eat etc.) does not appear to be deleterious.
- Constantly slightly low temperatures may result in slow development and late
hatching. If the temperature is maintained at a sufficiently low level, deaths
- A temperature which is too high by a few degrees may be lethal and even a rise of
just 1.0-1.5 °C (2-3 °F) may cause embryo death after perhaps four or five days.
- See: Early-Embryonic-Death, Mid-incubation Embryo Death,
Dead-in-Shell, Hatching Problems, Congenital Abnormalities
- Humidity levels can be measured with a wet-bulb thermometer.
- A wet-bulb thermometer is an ordinary thermometer in which the bulb is kept damp
by means of a "wick" of covering the bulb and dipped into a small container of
water. Evaporation from the wick reduces the temperature of the thermometer bulb.
- Since evaporation is greater in a drier environment, a lower temperature reading
indicates a lower humidity and a higher temperature reading indicates a higher humidity. A
dirty wick gives a falsely high reading. The distance from the thermometer to the water
reservoir for the wick should be about one inch (2.5 cm).
- Relative humidity is proportional to the wet bulb reading if the dry bulb reading
is constant. Tables indicating relative humidity for different wet bulb readings at
different dry bulb temperatures are available in some incubation texts (e.g. B42, B115.4.w1,
- All incubators contain some method of maintaining humidity. Humidity is usually
manipulated by changing the surface area of water trays placed in the bottom of the
incubator - a larger surface area will produce a higher humidity. For example, trays may
have a sloping floor, in which case increasing the depth of water will increase the
surface area. Alternatively, surface area may be increased by placing sponges into the
water with part of their surface coming out of the water.
- N.B. humidity will drop when the incubator is opened and,
particularly in a still air incubator, may take some time to return to the previous level.
Spraying the floor of the incubator lightly with water before closing the incubator door
may be used to increase the rate at which humidity is restored.
Weight loss during incubation:
- Eggs normally lose a total of 18% of their weight during incubation, due to loss
of water vapour which diffuses across the egg shell (J55.76.w1).
Eggs should lose 15% of their weight from the start of incubation to the start of hatching
(internal pipping). Monitoring and if necessary manipulation of their weight loss may be
used to improve hatching success.
- For ideal results, each egg should be weighed individually on an accurate balance
and the actual weight loss plotted on a graph and compared with the ideal weight loss for
that egg. This may be done by hand or using an appropriate computer
- The correct rate of weight loss early in incubation appears
particularly important for hatchability; incorrect early rates of weight loss may be fatal
to the embryo despite later correction giving the required overall weight loss.
- If weight loss is too fast or too slow, it may be manipulated. N.B.
Correcting the rate of weight loss after the first third of incubation is much more
- If several incubators are kept at slightly different relative
humidities, an egg
may be moved into an incubator at higher humidity if it is losing weight too fast, or
lower humidity if it is not losing weight sufficiently fast. Other methods involve
altering the porosity of the egg shell.
- N.B. in general, eggs which are normally incubated in very damp
conditions are likely to require a higher level of humidity during incubation than eggs
which would be incubated in the wild in very dry conditions.
Excessive weight loss and its correction
- Weight loss may be too fast due to thin shells or low incubator humidity.
- Weight loss may be decreased by increasing the incubator
- Part of the eggshell may be painted over with nail varnish to
decrease water loss through the shell.
- In extreme cases of excessive weight loss, rehydration may be used.
completely submerging the egg in cold (approximately 10°C, 50°F) sterile water for up to
five minutes (shorter times are preferable) daily or even more frequently, with accurate weighing to monitor the
uptake of water during the procedure. The cold temperature causes the egg contents to
contract, drawing water into the egg. The frequency and duration of dipping should be
varied according to the degree of weight loss and the stage of incubation. Care must be
taken not to over stress the embryo by dipping for too long. Dipping in antibiotic
solution has been described for the first dip (3 mg tylosine tartrate
Elanco Animal Health) in 1 litre sterile 0.9% saline giving 3000 parts per million
tylosin solution). (B42,
Insufficient weight loss and its correction
Incorrect humidity and egg weight loss may lead to loss of embryos or
chicks at several stages of incubation and hatching. See: Early-Embryonic-Death, Mid-incubation Embryo Death,
Dead-in-Shell, Hatching Problems
loss may be too slow due to thick shells or high incubator humidity.
- Weight loss may be increased by decreasing the incubator humidity.
- Porosity (and therefore water loss) may be increased by careful thinning of the
eggshell using sandpaper.
- Either automatic or hand turning may be used.
- If eggs are turned by hand they should be turned several times per day (minimum
five times daily), and always turned an odd number of times so that the egg is on opposite
sides for the longest internal (overnight) on alternate nights.
- Eggs should be marked with "O" on one side and "X" on
the opposite side, and all turned so that the "O" is uppermost on all the eggs
after one turning and the "X" is uppermost after the following turning.
- Eggs should be turned in one direction one day and the other direction
the following day (i.e. rotated along their long axis clockwise and anticlockwise
alternately). Continual rotation in the same direction may lead to problems such as
twisting of the chalazae, rupture of the yolk sac or rupture of blood vessels in the
- Various means of automatic turning may be used. Eggs may be laid on their
sides on rollers which move one way then the other alternately, or on a flat tray with
movement provided by the movement of rods one way then the other (or the rods may stay
still while the tray moves). An alternate method involves eggs being placed small end
downwards in trays which are tilted to 45 degrees one way then 45 degrees the other way.
- N.B. if automatic turning is used, monitoring is
required at different times of day to confirm that the eggs are being turned.
- See: Early-Embryonic-Death, Mid-incubation Embryo Death,
Dead-in-Shell, Hatching Problems
- Developing embryos require a flow of air to provide oxygen for
respiration and to remove carbon dioxide.
- Rigid egg trays with an open mesh construction should be used to allow
air to flow around the eggs and the addition of extra obstructions to air flow should be
- N.B. Air flow is lower in still air than in forced-air
incubators and it is important not to overcrowd the eggs.
- The movement of air in an incubator containing eggs will be different
from in the same incubator when empty, which is one reason why the incubator function
should be checked with bantam eggs.
- Temperatures within the incubator may fluctuate if air flow is
obstructed. If this cannot be rectified it is important to place eggs only in the most
stable temperature areas of the incubator.
- See: Early-Embryonic-Death, Mid-incubation Embryo Death,
Dead-in-Shell, Hatching Problems
- The development of the embryo within the egg is monitored most commonly
by means of candling - shining a bright light through the egg (see: Candling). Candling is difficult if
eggs have a very thick or patterned shell.
- Eggs may also be tested by Egg Floatation. The egg is placed in a bowl or bucket of water. Fresh eggs will sink,
late-incubation eggs will float and live eggs close to incubation can be seen to move.
- Accurate and detailed records are very important in incubation.
- In addition to records of individual eggs (see above: Introduction and General
Information) it is important to keep records of the temperature (dry bulb) and the
humidity (from wet bulb) of each incubator, so that increases or decreases in temperature
or humidity are detected early and can be corrected.
- Trends in temperature and humidity may be most easily seen if plotted on a graph.
- Temperature and humidity should be recorded at least two or three
times per day.
- Automatic turners should be checked at different times of the day to
confirm that they are actually operating and turning the eggs.
B42, B106, B115.4.w1, B119.w1,
- Removes the risk of egg breakage or abandonment by incubating
- It is very useful for ensuring proper incubation of eggs of
inexperienced or unreliable cranes. (P76.1989.w1)
- Safe from predation. (B115.4.w1)
- Keeps the egg clean and free of faeces, soil etc. (B115.4.w1)
- Removes the risk of disease transmission from the parents to the
egg or newly-hatched chick. (B115.4.w1)
- The egg can be monitored closely, e.g. for correct weight loss and
embryo development. (B115.4.w1)
- This method is essential for damaged (cracked) eggs or those with
thin shells. (B115.4.w1)
- This allows incubation following injury or death of the parents. (P76.1989.w1)
- This allows multiple clutching. (P76.1989.w1)
- There is a risk of losing many eggs if an incubator fails.
- Incubators do not provide the same temperature gradient from top to
bottom of the egg that is produced by a bird sitting on the eggs, nor
the same turning, nor the temperature variations seen at change-over time of
incubation, not the fluctuation associated with ambient temperature
- Biotelemetric monitoring of an artificial egg in the nest of a
pair of white-naped cranes showed that: (P76.1989.w1)
- eggs are turned approximately every hour, but when they are
turned they are turned several time over a period of up to ten
- The mean maximum egg temperature was 38.0 C. (P76.1989.w1)
- There was a considerable vertical thermal gradient - from
13.8 C on day one of incubation to 5.9 degress on day 29;
overall, the thermal gradient around the egg decreased during
incubation. However, the significance of the temperature
gradient in terms of embryo development is unknown. (P76.1989.w1)
- Nest humidity varied considerably depending on ambient air
- Video recordings showed that the female was on the nest
66.5% of the time, incubating for a mean of 69.2 minutes (for
32 incubation bouts) while the male was on the nest 26.7% of
the time, incubating for a mean of 32.2 minutes (for 38
incubation bouts. Neither bird was incubating for 6.9% of the
time; on average, the time off the nest between incubation
bouts was only 3.9 minutes (range 1.2 - 9.5 minutes). (P76.1989.w1)
- Note: Results may be improved if the eggs are incubated by
cranes initially (e.g. for the first two weeks). (B521.19.2.w19b)
Egg handling and initial care
- Always handle the eggs using clean or sterile latex, plastic or
vinyl gloves. (B115.4.w1,
- Wipe off any faeces or dirt using a soft cloth. (B115.4.w1)
- Stubborn, dried-on materials can be removed with fine sandpaper,
but great care must be taken not to damage the surface of the egg. (B115.4.w1)
- Weigh the egg and measure it (length and diameter). (P90.1.w2)
- Write an identifying number on the small end of the egg in pencil. (J23.21.w4, P90.1.w2)
- Before putting the egg in the incubator, fumigate the eggs (see Formaldehyde Fumigation of Incubators).
NOTE: only fresh eggs (not incubated at all) or eggs which have
been incubated for at least five days can be fumigated.
- OR as an alternative to fumigation, particularly for eggs
which may have been incubated for up to five days, or for an unknown
time, dip the egg in 10% povidone-iodine solution at 43.3 °C /
110 °F, then allow the egg to dry at room temperature before placing
it in the incubator. (B115.4.w1)
- Eggs can be dipped in a 20% quaternary ammonium solution or 1%
betadine solution. (P90.1.w2)
- Eggs can be stored for up to 10 days before incubation is started. (J23.14.w5)
- Store in cool conditions (12.8 C), horizontally, and turn 180
degrees daily. (J23.14.w5)
- Allow cool eggs to warm to room temperature before placing them
in the incubator. (J23.14.w5)
The correct incubation conditions are extremely important.
- An alarm should be installed, set to sound if there is a
power outage or the incubation temperature moves outside set
parameters: above 38.3 °C (101 °F) or below 35.6 °C (96 °F). As
well as an audible alarm in/near the incubation room, an alarm with an
autodialler should be installed which will alert personnel even away
from the incubator room. A flashing light may be used as an additional
Temperature and temperature control
- The correct temperature (dry-bulb temperature) for crane eggs is
37.6 °C (99.5 - 99.75 °F). (B115.4.w1,
- Temperature should be 36.5 - 38 °C. (P91.1.w6)
- 37.6 °C (99.5 °F)
- Regular cooling of eggs, as occurs during natural incubation e.g. at
nest exchanges, does not appear to improve hatchability of crane eggs, therefore maintenance in the incubator, in stable
conditions, except while candling etc., is recommended. (B115.4.w1,
- For each incubator there should be a main controlling thermostat
plus a backup thermostat which takes over control if the main
thermostat fails. (B115.4.w1)
- a rise in temperature of just 1.0-1,5 °C (2-3 °F) may be fatal,
not necessarily immediately but after 4-5 days. (B115.4.w1)
- a small drop in temperature below recommended is unlikely to
increase mortality but may slow the development of embryos,
delaying hatching. (B115.4.w1)
- Each incubator should contain a dry-bulb thermometer which can be
read from outside the incubator. (B115.4.w1)
- Each year, thermometers accurate to 0.1 °C (0.2 °F) should be
positioned in various places round the incubator to map the
temperature variation within the incubator. (B115.4.w1)
- Readings should be taken regularly several times a day and recorded. (B115.4.w1)
- Note: opening the incubator causes the temperature to drop.
When eggs need to be added or removed, carry this out carefully but
rapidly, to minimise the time for which the door is open. (B115.4.w1)
- The stability of the temperature inside the incubator is dependant
on stable ambient conditions within the incubator room. (B115.4.w1)
Humidity level and humidity control
- The correct humidity varies between crane species: (B115.4.w1, J23.21.w4)
- Note: if the local humidity is high, adjust to give a
wet-bulb temperature 1 °C (1-2 °F) lower than those suggested. If
your facility is at high altitude with a lower air pressure, adjust 1
°C (1-2 °F) upwards on the wet bulb temperature. (B115.4.w1)
- Wet-bulb thermometers indicate humidity as follows: the bulb of the
thermometer is covered by a cotton wick which reaches into a reservoir
of distilled water (so remains wet). The bulb of the thermometer is
cooled by water evaporating from the wick. As the relative humidity
increases, less water evaporates from the wick so the wet bulb
temperature rises to closer to the dry bulb temperature. (B115.4.w1)
- Humidity inside the incubator is controlled by evaporation of water
from a reservoir, misting, and air flow through the incubator.
Evaporation (and therefore humidity) can be increased by increasing
the surface area of a water tray and/or by ensuring that the fan of
the incubator blows air directly across the water tray. (B115.4.w1)
- Distilled water can be used to prevent build up of minerals. (B115.4.w1)
- Very large incubators may have a flow-through humidifying system
which makes use of distilled water too costly. (B115.4.w1)
- Note: opening the incubator causes the humidity to drop (as
well as the temperature). It takes longer for the humidity to rise
again after the door is closed than for the temperature to rise.
Before closing the door, lightly spray the incubator floor with water
to assist in raising the humidity more rapidly back to the usual
- A constant flow of oxygenated air is needed to provide oxygen to the
developing embryos in the eggs and remove carbon dioxide. Egg trays
should have a rigid, open mesh construction to enable air to flow
around the eggs.
- To avoid disrupting the air flow, keep all trays in the incubator,
and avoid adding obstructions.
- If air circulation is poor, there will be temperature variations
within the incubator.
- If temperature variations continue to be a problem, eggs should be
placed only where the temperature is most stable.
- Air flow is controlled by vents: more air flow (and therefore lower
humidity) when the vents are open, less (and therefore higher
humidity) when they are closed. Note: it is important to keep
the vents partially open at all times except during fumigation, to
ensure sufficient air flow to the embryos. (B115.4.w1)
Egg position and turning
- For automatically-turning incubators, make sure the eggs are placed
in the trays securely so they cannot move freely and break or
- Usually, set crane eggs horizontally so the big and small ends are
at the same height. (B115.4.w1)
- This position is used at ICF. At Patuxent, eggs are placed in
the trays such that they are at a 20-30 degree lateral angle when
the trays are flat, and as the trays tilt the large end is
elevated 20-30 degrees when the tray tilts forwards and the small
end is elevated 20-30 degrees when the tray tilts backwards.
Occurrence of chick malpositions (which can be associated with egg
positioning) is low at both facilities. (B115.4.w1)
- The intervals between eggs being turned should be equal. (B115.4.w1)
- If eggs are incubated horizontally it is important that successive
turns should be carried out in alternate directions (i.e. clockwise
then counterclockwise along the long axis of the egg) to make sure
that the chalazae (the albuminous cords attaching the yolk to the
shell membrane) do not get supercoiled. (B115.4.w1)
- If eggs are to be hand turned (i.e. if automatic turning is not
available) mark each egg with "X" on one side, "O"
on the other to show easily whether, and to what extent, an egg has
been turned. (B115.4.w1)
- Eggs should be turned at least eight times daily. (B115.4.w1)
- If an egg is not turned, the embryo may adhere to the shell
- The warm, humid conditions within an incubator are ideal for growth
of many pathogens. A clean, pathogen-free environment is required. (B115.4.w1)
- Before the onset of the laying season, thoroughly clean all surfaces
inside the incubator using a bactericidal and fungicidal disinfectant.
To clean the wiring, use compressed air or a light spray of
- Once clean, allow the incubator to dry, then turn it on and raise
the inside temperature to 26-37 C (80-100 F and relative humidity to
- If possible, fumigate the incubator, once it has reached working
conditions, using formaldehyde. See: Formaldehyde Fumigation of Incubators
- If fumigation cannot be carried out (e.g. for health and
safety reasons), use an appropriate egg safe commercial
During the laying season
- Incubators should be fumigated every two weeks, or weekly if eggs
are being added frequently (every few days). See: Formaldehyde Fumigation of Incubators
- Eggs which have been incubated for less than five days, or of
unknown stage of incubation need to be moved to another incubator
- Fresh (unincubated) eggs and eggs which have been incubated for
more than five days can be left in the incubator during
fumigation, to kill any pathogens on the shell.
- Incubator water trays need to be cleaned and disinfected regularly.
- If fumigation cannot be used, use a commercial spray disinfectant
suitable for incubators and safe for eggs.
Monitoring (candling, weight loss, flotation) & Record keeping
- Eggs should be monitored by regular candling and, when appropriate,
- For very valuable eggs, weigh twice weekly. (B115.4.w1)
- Keep a record of weights and a graph showing weight loss. (B115.4.w1)
- Ideally, the egg should lose 15% (13-17%) of its original weight by
the time of hatching. (B115.4.w1,
- Eggs which lose more or less than this amount may still hatch,
either with or without assistance.
- The temperature and humidity inside each incubator should be checked
and recorded at least twice or three times per day.
- If an automatic turning system is in use, this should be monitored
to confirm that it is turning the eggs.
- Note: records not only allow early detection of trends such
as temperature or humidityincreases or decreases, but also can be used
to adjust incubator conditions if problems develop e.g. in
Problems and problem solving
Cracked or damaged eggs
- Damaged eggs need to be artificially incubated. (B115.4.w1)
- Seal hairline cracks with surgical-grade cyanoacrylate or with
candle wax (drip wax from a burning candle onto the shell). Ensure
that the sealer is only applied along the crack(s) as excessive
sealing can interfere with gas exchange and asphyxiate the embryo. (B115.4.w1)
- Larger cracks and crushed areas also can be sealed using candlewax
applied in the same manner (by dripping). (B115.4.w1)
- Alternatively, for large crushed areas, apply a thin layer of bone
cement over the affected area. (B115.4.w1)
- To repair a hole, glue a piece of sterilised eggshell over the hole,
or layer parafilm, gauze or tissue over the hole with glue.
- Always apply repairing materials to the smallest possible area to
avoid restricting gaseous exchange. (B115.4.w1)
- Sealing too much of the shell also can cause the embryo to orient
away from the sealed area, which may lead to malposition. (B115.4.w1)
- Note: if the shell membranes have been damaged, it is likely
that pathogens may have been introduced, or the yolk, embryo or blood
vessels may have been physically damaged. (B115.4.w1)
- In general, once pathogens enter the egg, little can be done. However,
sometimes infection of a contaminated egg can be prevented by dipping
the egg in disinfectant, or by injecting the egg with antibiotics. (B115.4.w1)
- Eggs which show signs of infection (odor, discolouration of egg
contents) or are known to contain a dead embryo should be removed from
the incubator immediately to avoid other eggs becoming contaminated. (B115.4.w1)
- Note: eggs can explode due to pressure of gasses formed
during decomposition; this scatters the eggs contents all over the
incubator, contaminating the incubator and the other eggs. (B115.4.w1)
- Eggs which are obviously contaminated, and at least some of those
containing dead embryos or which are presumed infertile, should be
cultured to detect microbial infections.
- The origin of infection must be investigated if an infection is
found. If there is a persistent problem of microbial contamination of
eggs, swabs must be taken and cultured from the incubator, egg
handling equipment and the birds (by cloacal swabs).
- The incidence of infection can be minimised by good hygiene (see
above): using sterile surgical gloves to handle eggs, plus scrupulous
disinfection of all surfaces the eggs contact. (B115.4.w1)
Excess weight loss
- This may be due to low humidity, high incubation temperature or an
eggshell which is too porous or abnormally thin. (B115.4.w1)
- See above (general information on Artificial Incubation) for further
Insufficient weight loss
- This may be due to high humidity, low incubation temperature, a
thicker than usual shell or one with blocked pores. (B115.4.w1)
- See above (general information on Artificial Incubation) for further
Malpositioned or floating air cell
- If the air space is floating or there are multiple bubbles, hatching
is unlikely. The egg may be bacterially or fungally infected. (B115.4.w1)
- If the air cell is stationary but displaced, the chick may die at
hatching either because it orients correctly to the large end of the
egg (but the air cell is not where it is needed for the chick to
breath), so it drown or suffocates unless it quickly breaks through
the outer shell) or it orients to the air cell and is otherwise
malpositioned and cannot hatch. (B115.4.w1)
- It may be possible to save such chicks by immediate assistance
at hatching. (B115.4.w1)
- If the egg is incubated large end upwards and turned by hand the
chick may hatch successfully. (B115.4.w1)