Cracking
The Shells
Incubation is the art of hatching eggs under hens or a machine. We used an Incubator a model Little Giant: 9200 still air with an egg turner and fan which was supposed to help hatching. While, I have had success in the past with five hens going broody I wanted to try a machine, which would allow me to hatch eggs even when the hens were not available.
The eggs came from my leghorns, not from store bought eggs which are not fertilized by a rooster. I followed the instructions I had, but after 21 days the eggs did not hatch. I had candled them (held them up to a light to see inside of them) at 7 and 14 days, discarding a dozen of them along the way which were not fertilized or obviously dead. I used this chart as a guide.
We broke them open on the 24th day, allowing extra time for larger chicken eggs to mature, since they may need more time to hatch. We did this so that we can better understand why they did not hatch and can learn what improvements we need to make to increase the hatchability of the future batches of eggs.
Things to Consider
We first determined what age the chicks were when they died as embryos by looking at physical features of the chicks such as eyes, feathers, air sack and the yolk. After grouping them we reviewed a sheet called "Trouble Shooting Hatching Problems"
and made a chart to see what factors were common in order to determine the cause. Improper temperature, improper humidity, forgetting to turn the eggs, inadequate ventilation, germs/bacteria and nutritional deficiency are the potential reasons why my eggs didn't hatch. Another cause of embryos dying in the 6-16 day range is diseased breeder flock. I ruled this one cause out because my flock was healthy and not showing any symptoms.
Additionally, breeders have to take in consideration if the parent stock is small, weak or deformed since the young might be or they will be carrying it in their genes (genetic makeup). For example with chickens you can breed to nice birds together and depending on how the genes combine the parents can throw the opposite; wide breasted parents can throw skinny birds.
Hatching Problems
A. The eggs are fertile, but there is none to very little development. This could have happened with ...
1. Over held eggs
2. Too cold or too warm
3. Roughly handled
4. Ungathered eggs
5. Diseases in the flock of breeding birds
B. Egg with decreased embryos from day 6-16. This could have happened with ...
1. Temperature high or low in incubator
2. Bad Ventilation
3. Unturned Eggs
4. Nutritional Deficiency
5. Germs infectivity
Another cause of embryos dying in the 6-16 day range is diseased breeder flock. I ruled this one out because my flock was healthy and not showing any symptoms and did not list it as a possible reason.
C. Completely formed embryo not hatched, unabsorbed yolk. This could have happened with ...
1. Handled tough
2. High temperature and low humidity for the first ten days
3. Forgetting to turn the eggs
4. Bad humidity final couple days
5. Germs infectivity
D. Completely formed embryo not hatched, absorbed yolk, egg pipped but dead in shell. This could have happened with ...
1. Improper temperature
2. Improper humidity
3. Forgetting to turn the eggs
4. Inadequate ventilation in the last few
days
5. Germs infectivity
6. Nutritional Deficiency
Information learned from a poultry seminar.
Questions you might want to know for the begainers
Q. What kind of machine is this (an incubator) and why do you use it?
A. Incubation is the art of hatching eggs under hens or a machine called an Incubator. We used an Incubator a model 9200 with an egg turner and fan which was supposed to help hatching.
Q. Where did the eggs come from? Can you use any eggs?
A.They came from my leghorns, not from store bought eggs which are not fertilized by a rooster.
Q. What are the parts of the incubator?
A.The parts of my incubator are an egg turner [it turns the eggs] and a fan [circulates the air for better hatching].
Q. Why are you breaking the eggs?
A. So we can better understand improvements to increase the hatchability of the eggs.
Q. At what point did you break the eggs?
A. We broke them on the 24th day. Generally chickens only need 21 days, though larger chickens may need more time to hatch.
Q. How do you know what age the chicks live to in the egg?
A. We look at physical features such as eyes, feathers, air sack and the yolk.
How old is this chick
First day
16 hours -- first sign of resemblance to a chick embryo
18 hours -- appearance of alimentary tract
20 hours -- appearance of vertebral column
21 hours -- beginning of nervous system
22 hours -- beginning of head
24 hours -- beginning of eye
Second day
25 hours -- beginning of heart
35 hours -- beginning of ear
42 hours -- heart beats
Third day
60 hours -- beginning of nose
62 hours -- beginning of legs
64 hours -- beginning of wings
Fourth day -- beginning of tongue
Fifth day -- formation of reproductive organs and differentiation of sex
Sixth day -- beginning of beak
Eighth day -- beginning of feathers
Tenth day -- beginning of hardening of beak
Thirteenth day -- appearance of scales and claws
Fourteenth day -- embryo gets into position suitable for breaking shell
Sixteenth day -- scales, claws, and beak becoming firm and horny
Seventeenth day -- beak turns toward air cell
Nineteenth day -- yolk sac begins to enter body cavity
Twentieth day -- yolk sac completely drawn into body cavity; embryo occupies practically all the space within the egg except the air cell
Twenty-first day -- hatching of chick
From A.L. Romanoff, Cornell University Extension Bulletin 205
Incubation Sanitizer- tagtrowl- positive residual egg cleaner
Poultry: Reproduction & Incubation
Testing incubated eggs for embryo development
Sometimes it is necessary to test the incubated eggs for fertility. If large numbers of infertile eggs are incubated, they can be found and discarded, and the extra space used for additional eggs. This test will not injure the young embryos and is reliable for eliminating eggs that will not hatch.
Make a tester or candler by placing a light bulb and fixture inside a cardboard box. Cut a small, round hole in the top or side of the box, and let a narrow beam of light escape from the box. You can see the internal features of the egg by placing it against the hole. A darkened room makes testing easier.
The eggs are normally tested after 4 to 7 days of incubation. Eggs with white shells are easier to test and can be tested earlier than dark shelled eggs. Two classes of eggs can be removed on the basis of this early test, "infertiles" and "dead germs." "Infertile" refers to an unfertilized egg or an egg that started developing but died before growth could be detected. "Dead germs" refers to embryos that died after growing large enough to be seen when candled.
An "infertile" appears as a clear egg except for a slight shadow cast by the yolk. A live embryo is spider-like in appearance, with the embryo representing a spider's body and the large blood vessels spreading out much like a spider's legs. A "dead germ" can be distinguished by the presence of a blood ring around the embryo. This is caused by the movement of blood away from the embryo after death.
If you are not sure whether the embryo is alive, place the egg back in the incubator and retest later. A second test can be made after 14 to 16 days of incubation. If the embryo is living, only one or two small light spaces filled with blood vessels can be seen, and the chick may be observed moving.
http://msucares.com/poultry/reproductions/poultry_testing_embryo.html
http://animalscience.ucdavis.edu/Avian/pfs33.htm
POULTRY FACT SHEET NO. 33
COOPERATIVE EXTENSION - UNIVERSITY OF CALIFORNIA
July 1999
COMMON INCUBATION PROBLEMS: CAUSES AND REMEDIES
R. A. Ernst, F.A. Bradley, M.E. Delany, U.K. Abbott and R.M. Craig
Animal Science Department, University of California, Davis, CA 95616
Observation: Excessive infertility for species
PROBLEM CAUSES REMEDIES
True infertility [Definition]
Poor insemination technique Inseminate more frequently at proper depth with good semen
Hens not inseminated, wrong male to female ratio Inseminate hens; replace males; use more males
Preferential mating in pen matings Mate hen with different male
Male sterility Change males
Males not mating Check for disease, nutrition problems, foot problems and social dominance of females
Males too old Use young males; reinforce natural with artificial insemination if old, valuable males must be used
Observation: Over 3% dead 1st 3 days of incubation
PROBLEMS CAUSES REMEDIES
Pre-oviposital death [Definition]
Inbred strains Avoid excessive inbreeding; use young males
Parthenogenesis in turkeys Do not use as breeders, toms and/or hens showing high incidence of parthenogenesis
Fertile, no development (FND) [Definition]
Eggs stored at too low temperature Store hatching eggs properly (550F to 680F) see PFS No. 22
Eggs stored too long Store chicken, pheasant, duck, goose and quail eggs no longer than one week; turkey and partridge eggs no longer than two weeks
Eggs washed at too high temperatures Dry clean eggs; eliminate dirties; lower temperatures of wash water slightly; produce clean eggs
Positive development (PD) [Definition]
Poor collection schedule during hot or cold weather When temperature in house or nest box exceeds 80° F, collect eggs several times during the day
Blastoderm without embryo (BWE) [Definition]
Improper storage temperature Store eggs properly (55° F to 68° F) see PFS No. 22
Cystic embryos [Definition]
Eggs stored too long Store chicken, pheasant, duck, goose and quail eggs no longer than one week; turkey and partridge eggs no longer than two weeks
Rough handling or shipping procedures Careful handling from time eggs are gathered until chicks or poults are hatched
Diseased flock (e.g. mycoplasmas, Newcastle disease) Inspect flock for general and specific health conditions
Aged or abnormal spermatozoa Check insemination technique; use young males
Eggs from inbred flock Some losses are unavoidable with inbreeding; change males and/or introduce new genetic stock
Improper egg storage temperature or pre-incubation temperature Do not allow eggs to pre-incubate; use correct setter temperature (99.5° F); check egg storage temperature
Eggs from hens housed above 5,000 feet Avoid high altitude
Observation: Over .5% Dead day 4 to transfer
PROBLEMS CAUSES REMEDIES
Many dead embryos Improper temperature Check thermometer for accuracy
Unknown power failure If power fails open machine until power is restored
Improper turning Turn eggs three or more times each day
Eggs from inbred stocks Avoid excessive inbreeding
Poor ventilation of hatchery or incubator Provide proper air exchange
Disease or infected eggs Use eggs from disease-free flocks; Do not wash eggs in cold water
Observation: Over 8% dead after transfer
PROBLEMS CAUSES REMEDIES
Embryos dying before pipping Low temperature incubating conditions; humidity too high. Maintain 99.5° F dry-bulb, 86° F wet-bulb temperature in fan ventilated setter
Infected eggs Do not wash eggs in cold water; set only nest clean eggs
Poor nutrition of breeder flock Check breeder diet; nearly all known vitamins and minerals, if absent or in short supply, can cause late mortality and poor chick quality
Certain genetic lethals Use vigorous strains
Embryos weak and fail to pip or pip weakly Vitamin E deficiency Use fresh feed or supplement Vitamin E in water
Many pips stuck to shell Hatcher humidity too low Maintain 90° F wet-bulb temperature after pipping begins
Excessive residual albumen caused by high humidity and/or low temperature incubation Check thermometers and thermostats; monitor temperature and humidity
Chicks pipped and dead Disease Use disease free stock
Overheating in hatcher; low hatcher humidity Check hatcher temperature and humidity
Nutritional deficiency Feed balanced diet
Malpositions [Definition]
Eggs set small-end up Position eggs properly in trays (large end up or horizontal)
Chicks hatch too early, are thin and noisy Temperature too high during incubation period Check thermometer; 1° F in excess of 99.5° F will cause approximately 24-hour earlier hatch
Chicks hatch late, are soft and lethargic Temperature too low and humidity too high during incubation period Check thermometer; 1° F below 99.5° F will cause late hatch
Old eggs Set only fresh eggs; allow extra time for hatch by setting old eggs early
Sudden losses at any time Improper fumigation Do not fumigate between 24 and 96 hours of incubation.
Mercury spilled in incubator or hatcher Check for broken thermometer or thermostat; clean up all spilled mercury immediately
Power or equipment failure or overheating Check incubator temperature at least twice daily; refer to owners manual for proper maintenance procedure
Loss of incubated eggs from modern, high-hatching chicken strains, stored under optimal conditions, should be no more than 10 percent at the first candling. Losses in turkey, waterfowl and game bird eggs may be slightly higher. The mortality measured by candling and breakout during the first period will normally represent one third of the total to be expected. The mortality after the second candling should represent two thirds of the total with very little mortality during mid-incubation. Mortality during mid-incubation may indicate a dietary deficiency if infected embryos or developmental abnormalities are not seen. However, the most common nutrient deficiencies seen by the authors result from marginal vitamin levels and usually cause weak chicks which have difficulty hatching without other symptoms.
When eggs are candled after the first mortality peak at 7 to 10 days, three distinct classes can be recognized:
1. Living Normal embryos
2. Blood Rings (definition)
3. Clears
When eggs are candled at transfer clears are not expected unless they were missed on the first candling. Dead embryos should be expected in small numbers. Some of these may be associated with poor or damaged shells which were not removed during the first candling or which occurred after the first candling. Break out may reveal infected eggs which can be detected by abnormal color and odor.
When eggs which fail to hatch are examined several types of abnormalities are likely. The technician should look for malpositioned embryos (other than head under right wing and in the large end of the egg). Excessively wet or dry embryos indicate incorrect incubator humidity, extended or improper egg storage (dry) or poor shell quality. Some genetically abnormal embryos are expected at this stage but if numbers are excessive a more detailed investigation is advisable.
Life in Twenty-one Days
One of the greatest miracles of nature is the transformation of the egg into the chick. A chick emerges after a brief three weeks of incubation. The complexity of the development cannot be understood without some explanation of embryology.
Cell division begins soon after fertilization, even while the rest of the egg is being formed. Cell division will continue if the egg is kept warmer than 80 °F. The first cell division is completed about the time the egg enters the isthmus. Additional cell divisions take place about every 20 minutes, so by the time of lay, several thousand cells form two layers of cells called a "gastrula."
At this time the egg is laid, it cools, and embryonic development usually stops until proper environmental conditions are reestablished for incubation. After incubation begins, the cellular growth resumes. At first, all the cells are alike, but as the embryo develops, you can see cell differences. Some cells may become vital organs; others become a wing or leg.
Soon after incubation is begun, a pointed thickened layer of cells becomes visible in the caudal or tail end of the embryo. This pointed area is the primitive streak and is the longitudinal axis of the embryo. Before the first day of incubation is through, many new organs are forming. The head of the embryo becomes distinguishable; a precursor of the digestive tract, the foregut, is formed; blood islands appear and will develop later into the vascular or blood system; the neural fold forms and will develop into the neural groove; and the eye begins.
On the second day of incubation, the blood islands begin linking and form a vascular system, while the heart is being formed elsewhere. By the 44th hour of incubation, the heart and vascular systems join, and the heart begins beating. Two distinct circulatory systems are established, an embryonic system for the embryo and a vitelline system extending into the egg.
In later stages of embryonic development, there are two distinct extra-embryonic blood systems. One system, the vitelline system, transports nutrients from the yolk to the growing embryo. Before the fourth day, it oxygenates blood. The other blood system, made of allantoic vessels, is concerned with respiration and the storage of waste products in the allantois. When the chick hatches, both circulatory systems cease to function.
On the second day the neural groove forms and the head portion develops into the parts of the brain. The embryo is developed enough that flexion and arching of the embryo begins, the ears begin development, and the lenses in the eyes are forming.
At the end of the third day of incubation, the beak begins developing and limb buds for the wings and legs are seen. Three visceral clefts (gills) have formed on each side of the head and neck. These formations are important in the development of the arterial system, eustachian tube (in the ear), face, jaw, and some ductless glands. The fluid-filled amnion has surrounded the embryo to protect it: it helps maintain proper embryonic development. The tail appears, and the allantois is seen. The allantoic vesicle is a respiratory and excretory organ. Nourishment from the albumen and calcium from the shell are transported to the embryo through the allantois.
Torsion and flexion continue through the fourth day. The chick's entire body turns 90° and lies down with its left side on the yolk. The head and tail come close together so the embryo forms a "C" shape. The mouth, tongue, and nasal pits develop as parts of the digestive and respiratory systems. The heart continues to enlarge, even though it has not been enclosed within the body. It is seen beating if the egg is opened carefully. The other internal organs continue to develop. By the end of the fourth day of incubation, the embryo has all organs needed to sustain life after hatching, and most of the embryo's parts can be identified. The chick embryo cannot, however, be distinguished from that of mammals.
Many complex physiological processes take place during the change from the egg to the chick. They include the use of highly nutritious food materials in the egg; the respiration of gases, or the taking in of oxygen and the removal of carbon dioxide and the building of living energy within the chick.
The embryo grows and develops rapidly. By the seventh day digits appear on the wings and feet, the heart is completely enclosed in the thoracic cavity, and the embryo looks more like a bird. After the tenth day of incubation, feathers and feather tracts are visible and the beak hardens. On the fourteenth day the claws are forming and the embryo is moving into position for hatching. The supply of albumen is exhausted by the sixteenth day, so the yolk is the sole source of nutrients. After 20 days the chick is in the hatching position, the beak has pierced the air cell, and pulmonary respiration has begun. The yolk sac is contained completely within the body cavity in preparation for hatching.
The normal position of the chick for hatching is with the head in the large end of the egg, under the right wing, with the legs drawn up toward the head. If the head is positioned in the small end of the egg, the chick's chances of survival are reduced by at least one-half. This is a serious malposition, or wrong position, for hatching. Just as a wrong position makes birth more difficult in mammals, a wrong position of the chick makes hatching more difficult or impossible.
After 21 days of incubation, the chick finally begins its escape from the shell. The chick begins by pushing its beak through the air cell. The allantois, which has served as its lungs, begins to dry up as the chick uses its own lungs. The chick continues to push its head outward. The sharp horny structure on the upper beak (egg tooth) and the muscle on the back of the neck help cut the shell. The chick rests, changes position, and keeps cutting until its head falls free of the opened shell. It then kicks free of the bottom portion of the shell. The chick is exhausted and rests while the navel openings heal and its down dries. Gradually it regains strength and walks. The incubation and hatching are complete. The horny cap will fall off the beak within days after the chick hatches.
Newly-hatched chicks can be shipped long distances (up to 72 hours travel time) without food. You must provide chicks with feed and water on the first day of life so they can learn to eat and drink immediately. The yolk is largely unused by the embryo and is deposited within the chick's body on the 19th day, just before it hatches. The yolk is highly nourishing and provides proteins, fats, vitamins, minerals, and water for several hours after hatching. The yolk is consumed gradually during the first 10 days of the chick's life.
Incubating and Hatching Chicks
Getting and Caring for Hatching Eggs
In urban areas, getting hatching eggs may be a problem. Remember: eggs purchased from your local grocery store are not fertile and will not hatch. Egg producers supplying the stores with market eggs do not keep roosters with hens.
You can buy hatching eggs from most poultry breeding farms. For a list of hatching egg sources, contact your county agent. If possible, go to the farm and bring the eggs home yourself rather than having them shipped or mailed. It is difficult for the post office or transport companies to provide proper shipping conditions for small orders of hatching eggs.
Often careful attention is given to incubating and rearing chicks but none given to the care of the eggs before incubation. As we learned earlier, embryo development occurs even before the egg is laid. The best hatching eggs will suffer with reduced hatchability unless provided with proper care between oviposition and incubation.
It may not be practical for you to place the eggs in an incubator as soon as you get them. If not, keep them in a cool, humid room. The best storage conditions are near 55 °F. with 75 percent humidity. The vegetable section of your refrigerator is a suitable area. The temperature should not drop below 40 °F., or hatchability will be reduced. The cool temperature will delay embryonic growth until incubation begins, and the high humidity will keep the eggs from drying out.
Incubate the eggs as soon as possible to prevent reduction in hatchability. The hatchability of eggs older than seven to ten days decreases rapidly; at three weeks it reaches zero percent. If the eggs are not incubated within three to four days, turn them daily. Turning the eggs prevents the yolks from touching the shell and injuring the embryo. Plan ahead to avoid storage problems and reduced hatches.
Don't save excessively dirty eggs for hatching. These eggs can contaminate other eggs or chicks. Clean slightly soiled eggs by sanding them lightly with fine sandpaper. Don't sand them hard enough to make the shell thin or weak. Never wash hatching eggs, because this forces bacteria through the shell and into the egg.
The eggs should warm to room temperature before being placed in the incubator. The shock of warming the eggs too rapidly will cause moisture to condense on the shell; this may lead to disease or a reduced hatch.
Incubation Procedures
Because the incubator is not well insulated and will be opened frequently when the eggs are turned, keep the machine in a room where the temperature is between 70° and 75 °F. (Normal room temperatures are satisfactory.) Do not place the incubator near windows where it may be exposed to the direct rays of the sun or near cold walls.
Two basic types of incubators are available: forced-air and still-air incubators. In forced-air incubators, fans provide internal circulation. The capacity of these units may be large. The still-air incubators are usually small and have no fans for air circulation. Air exchange is made by escaping warm, stale air at the top and entering cooler, fresh air at the bottom. Recommended temperature will vary between the two incubators, so follow the manufacturer's recommendations. All references to incubators are directed to the still-air incubators except where noted.
Clean and disinfect the incubator before each use. Wash the unit with a warm detergent solution and rinse with a disinfectant solution. This reduces the chances of carrying disease-causing organisms from one batch of eggs to another.
Start the incubator a day or two before setting the eggs. Turn on the heat and place water in the tray so you may have proper incubation conditions. Place a thermometer in the incubator so the bulb is one inch above the screen floor, close the incubator, and adjust the thermostat until the temperature stays between 101° and 102 °F. Be careful that the bulb of the thermometer does not touch the eggs or side of the incubator. The sides and top of the incubator should fit together securely to prevent heat loss.
To get the best possible hatch, keep the temperature as close to 102 °F. as possible for the complete incubation period. There will be minor fluctuations of 1 degree F. above and below the desired temperature, but there should not be prolonged periods of high or low temperatures. Hatching eggs can take an amazing amount of abuse because they are well protected and insulated, but they are sensitive to extreme heat. Operating the incubator at 105 °F. for 30 minutes will harm many embryos, but operating at 90 °F. for three to four hours will merely slow the rate of growth.
Check the thermometer! Is it accurate? An error of one degree for 21 days can seriously interfere with an embryo's growth. To check the incubator thermometer, place the bulb next to the bulb of a clinical (oral kind used to check body temperature) or a laboratory thermometer. Hold them under lukewarm water and compare the readings. Both should read the same temperature, so make adjustments for any error in the incubator thermometer. A thermometer in which the mercury column is separated will not give an accurate reading. Discard it.
Humidity must be carefully controlled to prevent unnecessary moisture loss from the eggs. A device often used to measure humidity inside an incubator is the hygrometer. Readings from a hygrometer are measured in "degrees, wet bulb." Use the table to convert hygrometer readings to relative humidity. The relative humidity in the incubator for the first 18 days should remain at 58-60 percent of 87° to 89 °F., wet bulb. Increase the humidity during the last three days of incubation to at least 65 percent relative humidity or 90° to 94 °F., wet bulb.
Wet Bulb vs. Relative Humidity
Relative Humidity Wet Bulb Readings
Temp., °F.
99 100 101 102
45 80.5 81.3 82.2 83.0
50 82.5 83.3 84.2 85.0
55 84.5 85.3 86.2 87.0
60 86.5 87.3 88.2 89.0
65 88.0 89.0 90.0 91.0
70 89.7 90.7 91.7 92.7
An excellent way to determine if proper humidity is maintained is to candle the eggs. As incubation progresses, the air cell of the egg becomes larger because moisture is lost from the egg. You can make necessary humidity adjustments as a result of the candling inspection. Here's what the air sack should look like on various days.
Rarely is the humidity too high in a still-air incubator. The water pan should cover at least one-half of the surface area of a still-air incubator. At hatching time, place another pan of water or a wet sponge in the incubator to increase the humidity by increasing the exposed water surface area. Chicks need to be saturated before they can hatch properly, but do not drown them. High humidity will produce a late hatch; low humidity will produce an early hatch. Low humidity will also cause the chick to stick in the shell and die at hatching time.
Proper ventilation is vital. During embryonic development, oxygen enters the egg through pores in the shell, and carbon dioxide escapes in the same manner. As the chicks begin to hatch, they must receive an increasing supply of fresh air. As the embryos grow, gradually open the air openings of the incubator to increase the air flow. Be sure to avoid reducing the humidity during the hatching period. Provide ventilation openings both above and below the eggs for proper air exchange. Never place more than one layer of eggs in a still-air incubator.
If the electric power fails, the eggs will fare best if left alone to conserve the heat and humidity within the incubator. If the incubator is the forced-air type, open the incubator immediately and let fresh air enter. Maintain the room temperature at 75 °F. or more.
Turn the eggs at least two or three times daily during the first 18 days of incubation. Turning keeps the embryo from sticking to the shell membranes when left in one position too long. DO NOT turn eggs during the last three days before hatching. The embryos are moving into hatching position and do not need to be turned.
An excellent method to tell if all eggs have been turned is to mark an "X" on one side of the shell and an "O" on the opposite side. You can always tell if the eggs have been turned by noting which side is up. Write the marks with a pencil so harmful chemicals do not enter the eggs. When turning, be sure your hands are clean and free of greasy or dusty substances. During the first week in incubation, turn eggs carefully because the developing embryos have delicate blood vessels that may be ruptured if jarred or shaken.
Mark eggs incubated on different days with the date you placed them in the incubator. This prevents eggs from being overlooked and left in the incubator after they should have hatched. The eggs should be set and maintained vertically with the large end up or horizontally with the large end slightly elevated. This will let the embryo stay in the proper position for hatching.
Chicken eggs require 21 days to hatch, but the incubation periods for the eggs of other species of poultry vary. The approximate periods of incubation required for various species of poultry and game birds are as follows:
http://www.poultryhelp.com/avianembryo.html
The Shells
Incubation is the art of hatching eggs under hens or a machine. We used an Incubator a model Little Giant: 9200 still air with an egg turner and fan which was supposed to help hatching. While, I have had success in the past with five hens going broody I wanted to try a machine, which would allow me to hatch eggs even when the hens were not available.
The eggs came from my leghorns, not from store bought eggs which are not fertilized by a rooster. I followed the instructions I had, but after 21 days the eggs did not hatch. I had candled them (held them up to a light to see inside of them) at 7 and 14 days, discarding a dozen of them along the way which were not fertilized or obviously dead. I used this chart as a guide.
We broke them open on the 24th day, allowing extra time for larger chicken eggs to mature, since they may need more time to hatch. We did this so that we can better understand why they did not hatch and can learn what improvements we need to make to increase the hatchability of the future batches of eggs.
Things to Consider
We first determined what age the chicks were when they died as embryos by looking at physical features of the chicks such as eyes, feathers, air sack and the yolk. After grouping them we reviewed a sheet called "Trouble Shooting Hatching Problems"
and made a chart to see what factors were common in order to determine the cause. Improper temperature, improper humidity, forgetting to turn the eggs, inadequate ventilation, germs/bacteria and nutritional deficiency are the potential reasons why my eggs didn't hatch. Another cause of embryos dying in the 6-16 day range is diseased breeder flock. I ruled this one cause out because my flock was healthy and not showing any symptoms.
Additionally, breeders have to take in consideration if the parent stock is small, weak or deformed since the young might be or they will be carrying it in their genes (genetic makeup). For example with chickens you can breed to nice birds together and depending on how the genes combine the parents can throw the opposite; wide breasted parents can throw skinny birds.
Hatching Problems
A. The eggs are fertile, but there is none to very little development. This could have happened with ...
1. Over held eggs
2. Too cold or too warm
3. Roughly handled
4. Ungathered eggs
5. Diseases in the flock of breeding birds
B. Egg with decreased embryos from day 6-16. This could have happened with ...
1. Temperature high or low in incubator
2. Bad Ventilation
3. Unturned Eggs
4. Nutritional Deficiency
5. Germs infectivity
Another cause of embryos dying in the 6-16 day range is diseased breeder flock. I ruled this one out because my flock was healthy and not showing any symptoms and did not list it as a possible reason.
C. Completely formed embryo not hatched, unabsorbed yolk. This could have happened with ...
1. Handled tough
2. High temperature and low humidity for the first ten days
3. Forgetting to turn the eggs
4. Bad humidity final couple days
5. Germs infectivity
D. Completely formed embryo not hatched, absorbed yolk, egg pipped but dead in shell. This could have happened with ...
1. Improper temperature
2. Improper humidity
3. Forgetting to turn the eggs
4. Inadequate ventilation in the last few
days
5. Germs infectivity
6. Nutritional Deficiency
Information learned from a poultry seminar.
Questions you might want to know for the begainers
Q. What kind of machine is this (an incubator) and why do you use it?
A. Incubation is the art of hatching eggs under hens or a machine called an Incubator. We used an Incubator a model 9200 with an egg turner and fan which was supposed to help hatching.
Q. Where did the eggs come from? Can you use any eggs?
A.They came from my leghorns, not from store bought eggs which are not fertilized by a rooster.
Q. What are the parts of the incubator?
A.The parts of my incubator are an egg turner [it turns the eggs] and a fan [circulates the air for better hatching].
Q. Why are you breaking the eggs?
A. So we can better understand improvements to increase the hatchability of the eggs.
Q. At what point did you break the eggs?
A. We broke them on the 24th day. Generally chickens only need 21 days, though larger chickens may need more time to hatch.
Q. How do you know what age the chicks live to in the egg?
A. We look at physical features such as eyes, feathers, air sack and the yolk.
How old is this chick
First day
16 hours -- first sign of resemblance to a chick embryo
18 hours -- appearance of alimentary tract
20 hours -- appearance of vertebral column
21 hours -- beginning of nervous system
22 hours -- beginning of head
24 hours -- beginning of eye
Second day
25 hours -- beginning of heart
35 hours -- beginning of ear
42 hours -- heart beats
Third day
60 hours -- beginning of nose
62 hours -- beginning of legs
64 hours -- beginning of wings
Fourth day -- beginning of tongue
Fifth day -- formation of reproductive organs and differentiation of sex
Sixth day -- beginning of beak
Eighth day -- beginning of feathers
Tenth day -- beginning of hardening of beak
Thirteenth day -- appearance of scales and claws
Fourteenth day -- embryo gets into position suitable for breaking shell
Sixteenth day -- scales, claws, and beak becoming firm and horny
Seventeenth day -- beak turns toward air cell
Nineteenth day -- yolk sac begins to enter body cavity
Twentieth day -- yolk sac completely drawn into body cavity; embryo occupies practically all the space within the egg except the air cell
Twenty-first day -- hatching of chick
From A.L. Romanoff, Cornell University Extension Bulletin 205
Incubation Sanitizer- tagtrowl- positive residual egg cleaner
Poultry: Reproduction & Incubation
Testing incubated eggs for embryo development
Sometimes it is necessary to test the incubated eggs for fertility. If large numbers of infertile eggs are incubated, they can be found and discarded, and the extra space used for additional eggs. This test will not injure the young embryos and is reliable for eliminating eggs that will not hatch.
Make a tester or candler by placing a light bulb and fixture inside a cardboard box. Cut a small, round hole in the top or side of the box, and let a narrow beam of light escape from the box. You can see the internal features of the egg by placing it against the hole. A darkened room makes testing easier.
The eggs are normally tested after 4 to 7 days of incubation. Eggs with white shells are easier to test and can be tested earlier than dark shelled eggs. Two classes of eggs can be removed on the basis of this early test, "infertiles" and "dead germs." "Infertile" refers to an unfertilized egg or an egg that started developing but died before growth could be detected. "Dead germs" refers to embryos that died after growing large enough to be seen when candled.
An "infertile" appears as a clear egg except for a slight shadow cast by the yolk. A live embryo is spider-like in appearance, with the embryo representing a spider's body and the large blood vessels spreading out much like a spider's legs. A "dead germ" can be distinguished by the presence of a blood ring around the embryo. This is caused by the movement of blood away from the embryo after death.
If you are not sure whether the embryo is alive, place the egg back in the incubator and retest later. A second test can be made after 14 to 16 days of incubation. If the embryo is living, only one or two small light spaces filled with blood vessels can be seen, and the chick may be observed moving.
http://msucares.com/poultry/reproductions/poultry_testing_embryo.html
http://animalscience.ucdavis.edu/Avian/pfs33.htm
POULTRY FACT SHEET NO. 33
COOPERATIVE EXTENSION - UNIVERSITY OF CALIFORNIA
July 1999
COMMON INCUBATION PROBLEMS: CAUSES AND REMEDIES
R. A. Ernst, F.A. Bradley, M.E. Delany, U.K. Abbott and R.M. Craig
Animal Science Department, University of California, Davis, CA 95616
Observation: Excessive infertility for species
PROBLEM CAUSES REMEDIES
True infertility [Definition]
Poor insemination technique Inseminate more frequently at proper depth with good semen
Hens not inseminated, wrong male to female ratio Inseminate hens; replace males; use more males
Preferential mating in pen matings Mate hen with different male
Male sterility Change males
Males not mating Check for disease, nutrition problems, foot problems and social dominance of females
Males too old Use young males; reinforce natural with artificial insemination if old, valuable males must be used
Observation: Over 3% dead 1st 3 days of incubation
PROBLEMS CAUSES REMEDIES
Pre-oviposital death [Definition]
Inbred strains Avoid excessive inbreeding; use young males
Parthenogenesis in turkeys Do not use as breeders, toms and/or hens showing high incidence of parthenogenesis
Fertile, no development (FND) [Definition]
Eggs stored at too low temperature Store hatching eggs properly (550F to 680F) see PFS No. 22
Eggs stored too long Store chicken, pheasant, duck, goose and quail eggs no longer than one week; turkey and partridge eggs no longer than two weeks
Eggs washed at too high temperatures Dry clean eggs; eliminate dirties; lower temperatures of wash water slightly; produce clean eggs
Positive development (PD) [Definition]
Poor collection schedule during hot or cold weather When temperature in house or nest box exceeds 80° F, collect eggs several times during the day
Blastoderm without embryo (BWE) [Definition]
Improper storage temperature Store eggs properly (55° F to 68° F) see PFS No. 22
Cystic embryos [Definition]
Eggs stored too long Store chicken, pheasant, duck, goose and quail eggs no longer than one week; turkey and partridge eggs no longer than two weeks
Rough handling or shipping procedures Careful handling from time eggs are gathered until chicks or poults are hatched
Diseased flock (e.g. mycoplasmas, Newcastle disease) Inspect flock for general and specific health conditions
Aged or abnormal spermatozoa Check insemination technique; use young males
Eggs from inbred flock Some losses are unavoidable with inbreeding; change males and/or introduce new genetic stock
Improper egg storage temperature or pre-incubation temperature Do not allow eggs to pre-incubate; use correct setter temperature (99.5° F); check egg storage temperature
Eggs from hens housed above 5,000 feet Avoid high altitude
Observation: Over .5% Dead day 4 to transfer
PROBLEMS CAUSES REMEDIES
Many dead embryos Improper temperature Check thermometer for accuracy
Unknown power failure If power fails open machine until power is restored
Improper turning Turn eggs three or more times each day
Eggs from inbred stocks Avoid excessive inbreeding
Poor ventilation of hatchery or incubator Provide proper air exchange
Disease or infected eggs Use eggs from disease-free flocks; Do not wash eggs in cold water
Observation: Over 8% dead after transfer
PROBLEMS CAUSES REMEDIES
Embryos dying before pipping Low temperature incubating conditions; humidity too high. Maintain 99.5° F dry-bulb, 86° F wet-bulb temperature in fan ventilated setter
Infected eggs Do not wash eggs in cold water; set only nest clean eggs
Poor nutrition of breeder flock Check breeder diet; nearly all known vitamins and minerals, if absent or in short supply, can cause late mortality and poor chick quality
Certain genetic lethals Use vigorous strains
Embryos weak and fail to pip or pip weakly Vitamin E deficiency Use fresh feed or supplement Vitamin E in water
Many pips stuck to shell Hatcher humidity too low Maintain 90° F wet-bulb temperature after pipping begins
Excessive residual albumen caused by high humidity and/or low temperature incubation Check thermometers and thermostats; monitor temperature and humidity
Chicks pipped and dead Disease Use disease free stock
Overheating in hatcher; low hatcher humidity Check hatcher temperature and humidity
Nutritional deficiency Feed balanced diet
Malpositions [Definition]
Eggs set small-end up Position eggs properly in trays (large end up or horizontal)
Chicks hatch too early, are thin and noisy Temperature too high during incubation period Check thermometer; 1° F in excess of 99.5° F will cause approximately 24-hour earlier hatch
Chicks hatch late, are soft and lethargic Temperature too low and humidity too high during incubation period Check thermometer; 1° F below 99.5° F will cause late hatch
Old eggs Set only fresh eggs; allow extra time for hatch by setting old eggs early
Sudden losses at any time Improper fumigation Do not fumigate between 24 and 96 hours of incubation.
Mercury spilled in incubator or hatcher Check for broken thermometer or thermostat; clean up all spilled mercury immediately
Power or equipment failure or overheating Check incubator temperature at least twice daily; refer to owners manual for proper maintenance procedure
Loss of incubated eggs from modern, high-hatching chicken strains, stored under optimal conditions, should be no more than 10 percent at the first candling. Losses in turkey, waterfowl and game bird eggs may be slightly higher. The mortality measured by candling and breakout during the first period will normally represent one third of the total to be expected. The mortality after the second candling should represent two thirds of the total with very little mortality during mid-incubation. Mortality during mid-incubation may indicate a dietary deficiency if infected embryos or developmental abnormalities are not seen. However, the most common nutrient deficiencies seen by the authors result from marginal vitamin levels and usually cause weak chicks which have difficulty hatching without other symptoms.
When eggs are candled after the first mortality peak at 7 to 10 days, three distinct classes can be recognized:
1. Living Normal embryos
2. Blood Rings (definition)
3. Clears
When eggs are candled at transfer clears are not expected unless they were missed on the first candling. Dead embryos should be expected in small numbers. Some of these may be associated with poor or damaged shells which were not removed during the first candling or which occurred after the first candling. Break out may reveal infected eggs which can be detected by abnormal color and odor.
When eggs which fail to hatch are examined several types of abnormalities are likely. The technician should look for malpositioned embryos (other than head under right wing and in the large end of the egg). Excessively wet or dry embryos indicate incorrect incubator humidity, extended or improper egg storage (dry) or poor shell quality. Some genetically abnormal embryos are expected at this stage but if numbers are excessive a more detailed investigation is advisable.
Life in Twenty-one Days
One of the greatest miracles of nature is the transformation of the egg into the chick. A chick emerges after a brief three weeks of incubation. The complexity of the development cannot be understood without some explanation of embryology.
Cell division begins soon after fertilization, even while the rest of the egg is being formed. Cell division will continue if the egg is kept warmer than 80 °F. The first cell division is completed about the time the egg enters the isthmus. Additional cell divisions take place about every 20 minutes, so by the time of lay, several thousand cells form two layers of cells called a "gastrula."
At this time the egg is laid, it cools, and embryonic development usually stops until proper environmental conditions are reestablished for incubation. After incubation begins, the cellular growth resumes. At first, all the cells are alike, but as the embryo develops, you can see cell differences. Some cells may become vital organs; others become a wing or leg.
Soon after incubation is begun, a pointed thickened layer of cells becomes visible in the caudal or tail end of the embryo. This pointed area is the primitive streak and is the longitudinal axis of the embryo. Before the first day of incubation is through, many new organs are forming. The head of the embryo becomes distinguishable; a precursor of the digestive tract, the foregut, is formed; blood islands appear and will develop later into the vascular or blood system; the neural fold forms and will develop into the neural groove; and the eye begins.
On the second day of incubation, the blood islands begin linking and form a vascular system, while the heart is being formed elsewhere. By the 44th hour of incubation, the heart and vascular systems join, and the heart begins beating. Two distinct circulatory systems are established, an embryonic system for the embryo and a vitelline system extending into the egg.
In later stages of embryonic development, there are two distinct extra-embryonic blood systems. One system, the vitelline system, transports nutrients from the yolk to the growing embryo. Before the fourth day, it oxygenates blood. The other blood system, made of allantoic vessels, is concerned with respiration and the storage of waste products in the allantois. When the chick hatches, both circulatory systems cease to function.
On the second day the neural groove forms and the head portion develops into the parts of the brain. The embryo is developed enough that flexion and arching of the embryo begins, the ears begin development, and the lenses in the eyes are forming.
At the end of the third day of incubation, the beak begins developing and limb buds for the wings and legs are seen. Three visceral clefts (gills) have formed on each side of the head and neck. These formations are important in the development of the arterial system, eustachian tube (in the ear), face, jaw, and some ductless glands. The fluid-filled amnion has surrounded the embryo to protect it: it helps maintain proper embryonic development. The tail appears, and the allantois is seen. The allantoic vesicle is a respiratory and excretory organ. Nourishment from the albumen and calcium from the shell are transported to the embryo through the allantois.
Torsion and flexion continue through the fourth day. The chick's entire body turns 90° and lies down with its left side on the yolk. The head and tail come close together so the embryo forms a "C" shape. The mouth, tongue, and nasal pits develop as parts of the digestive and respiratory systems. The heart continues to enlarge, even though it has not been enclosed within the body. It is seen beating if the egg is opened carefully. The other internal organs continue to develop. By the end of the fourth day of incubation, the embryo has all organs needed to sustain life after hatching, and most of the embryo's parts can be identified. The chick embryo cannot, however, be distinguished from that of mammals.
Many complex physiological processes take place during the change from the egg to the chick. They include the use of highly nutritious food materials in the egg; the respiration of gases, or the taking in of oxygen and the removal of carbon dioxide and the building of living energy within the chick.
The embryo grows and develops rapidly. By the seventh day digits appear on the wings and feet, the heart is completely enclosed in the thoracic cavity, and the embryo looks more like a bird. After the tenth day of incubation, feathers and feather tracts are visible and the beak hardens. On the fourteenth day the claws are forming and the embryo is moving into position for hatching. The supply of albumen is exhausted by the sixteenth day, so the yolk is the sole source of nutrients. After 20 days the chick is in the hatching position, the beak has pierced the air cell, and pulmonary respiration has begun. The yolk sac is contained completely within the body cavity in preparation for hatching.
The normal position of the chick for hatching is with the head in the large end of the egg, under the right wing, with the legs drawn up toward the head. If the head is positioned in the small end of the egg, the chick's chances of survival are reduced by at least one-half. This is a serious malposition, or wrong position, for hatching. Just as a wrong position makes birth more difficult in mammals, a wrong position of the chick makes hatching more difficult or impossible.
After 21 days of incubation, the chick finally begins its escape from the shell. The chick begins by pushing its beak through the air cell. The allantois, which has served as its lungs, begins to dry up as the chick uses its own lungs. The chick continues to push its head outward. The sharp horny structure on the upper beak (egg tooth) and the muscle on the back of the neck help cut the shell. The chick rests, changes position, and keeps cutting until its head falls free of the opened shell. It then kicks free of the bottom portion of the shell. The chick is exhausted and rests while the navel openings heal and its down dries. Gradually it regains strength and walks. The incubation and hatching are complete. The horny cap will fall off the beak within days after the chick hatches.
Newly-hatched chicks can be shipped long distances (up to 72 hours travel time) without food. You must provide chicks with feed and water on the first day of life so they can learn to eat and drink immediately. The yolk is largely unused by the embryo and is deposited within the chick's body on the 19th day, just before it hatches. The yolk is highly nourishing and provides proteins, fats, vitamins, minerals, and water for several hours after hatching. The yolk is consumed gradually during the first 10 days of the chick's life.
Incubating and Hatching Chicks
Getting and Caring for Hatching Eggs
In urban areas, getting hatching eggs may be a problem. Remember: eggs purchased from your local grocery store are not fertile and will not hatch. Egg producers supplying the stores with market eggs do not keep roosters with hens.
You can buy hatching eggs from most poultry breeding farms. For a list of hatching egg sources, contact your county agent. If possible, go to the farm and bring the eggs home yourself rather than having them shipped or mailed. It is difficult for the post office or transport companies to provide proper shipping conditions for small orders of hatching eggs.
Often careful attention is given to incubating and rearing chicks but none given to the care of the eggs before incubation. As we learned earlier, embryo development occurs even before the egg is laid. The best hatching eggs will suffer with reduced hatchability unless provided with proper care between oviposition and incubation.
It may not be practical for you to place the eggs in an incubator as soon as you get them. If not, keep them in a cool, humid room. The best storage conditions are near 55 °F. with 75 percent humidity. The vegetable section of your refrigerator is a suitable area. The temperature should not drop below 40 °F., or hatchability will be reduced. The cool temperature will delay embryonic growth until incubation begins, and the high humidity will keep the eggs from drying out.
Incubate the eggs as soon as possible to prevent reduction in hatchability. The hatchability of eggs older than seven to ten days decreases rapidly; at three weeks it reaches zero percent. If the eggs are not incubated within three to four days, turn them daily. Turning the eggs prevents the yolks from touching the shell and injuring the embryo. Plan ahead to avoid storage problems and reduced hatches.
Don't save excessively dirty eggs for hatching. These eggs can contaminate other eggs or chicks. Clean slightly soiled eggs by sanding them lightly with fine sandpaper. Don't sand them hard enough to make the shell thin or weak. Never wash hatching eggs, because this forces bacteria through the shell and into the egg.
The eggs should warm to room temperature before being placed in the incubator. The shock of warming the eggs too rapidly will cause moisture to condense on the shell; this may lead to disease or a reduced hatch.
Incubation Procedures
Because the incubator is not well insulated and will be opened frequently when the eggs are turned, keep the machine in a room where the temperature is between 70° and 75 °F. (Normal room temperatures are satisfactory.) Do not place the incubator near windows where it may be exposed to the direct rays of the sun or near cold walls.
Two basic types of incubators are available: forced-air and still-air incubators. In forced-air incubators, fans provide internal circulation. The capacity of these units may be large. The still-air incubators are usually small and have no fans for air circulation. Air exchange is made by escaping warm, stale air at the top and entering cooler, fresh air at the bottom. Recommended temperature will vary between the two incubators, so follow the manufacturer's recommendations. All references to incubators are directed to the still-air incubators except where noted.
Clean and disinfect the incubator before each use. Wash the unit with a warm detergent solution and rinse with a disinfectant solution. This reduces the chances of carrying disease-causing organisms from one batch of eggs to another.
Start the incubator a day or two before setting the eggs. Turn on the heat and place water in the tray so you may have proper incubation conditions. Place a thermometer in the incubator so the bulb is one inch above the screen floor, close the incubator, and adjust the thermostat until the temperature stays between 101° and 102 °F. Be careful that the bulb of the thermometer does not touch the eggs or side of the incubator. The sides and top of the incubator should fit together securely to prevent heat loss.
To get the best possible hatch, keep the temperature as close to 102 °F. as possible for the complete incubation period. There will be minor fluctuations of 1 degree F. above and below the desired temperature, but there should not be prolonged periods of high or low temperatures. Hatching eggs can take an amazing amount of abuse because they are well protected and insulated, but they are sensitive to extreme heat. Operating the incubator at 105 °F. for 30 minutes will harm many embryos, but operating at 90 °F. for three to four hours will merely slow the rate of growth.
Check the thermometer! Is it accurate? An error of one degree for 21 days can seriously interfere with an embryo's growth. To check the incubator thermometer, place the bulb next to the bulb of a clinical (oral kind used to check body temperature) or a laboratory thermometer. Hold them under lukewarm water and compare the readings. Both should read the same temperature, so make adjustments for any error in the incubator thermometer. A thermometer in which the mercury column is separated will not give an accurate reading. Discard it.
Humidity must be carefully controlled to prevent unnecessary moisture loss from the eggs. A device often used to measure humidity inside an incubator is the hygrometer. Readings from a hygrometer are measured in "degrees, wet bulb." Use the table to convert hygrometer readings to relative humidity. The relative humidity in the incubator for the first 18 days should remain at 58-60 percent of 87° to 89 °F., wet bulb. Increase the humidity during the last three days of incubation to at least 65 percent relative humidity or 90° to 94 °F., wet bulb.
Wet Bulb vs. Relative Humidity
Relative Humidity Wet Bulb Readings
Temp., °F.
99 100 101 102
45 80.5 81.3 82.2 83.0
50 82.5 83.3 84.2 85.0
55 84.5 85.3 86.2 87.0
60 86.5 87.3 88.2 89.0
65 88.0 89.0 90.0 91.0
70 89.7 90.7 91.7 92.7
An excellent way to determine if proper humidity is maintained is to candle the eggs. As incubation progresses, the air cell of the egg becomes larger because moisture is lost from the egg. You can make necessary humidity adjustments as a result of the candling inspection. Here's what the air sack should look like on various days.
Rarely is the humidity too high in a still-air incubator. The water pan should cover at least one-half of the surface area of a still-air incubator. At hatching time, place another pan of water or a wet sponge in the incubator to increase the humidity by increasing the exposed water surface area. Chicks need to be saturated before they can hatch properly, but do not drown them. High humidity will produce a late hatch; low humidity will produce an early hatch. Low humidity will also cause the chick to stick in the shell and die at hatching time.
Proper ventilation is vital. During embryonic development, oxygen enters the egg through pores in the shell, and carbon dioxide escapes in the same manner. As the chicks begin to hatch, they must receive an increasing supply of fresh air. As the embryos grow, gradually open the air openings of the incubator to increase the air flow. Be sure to avoid reducing the humidity during the hatching period. Provide ventilation openings both above and below the eggs for proper air exchange. Never place more than one layer of eggs in a still-air incubator.
If the electric power fails, the eggs will fare best if left alone to conserve the heat and humidity within the incubator. If the incubator is the forced-air type, open the incubator immediately and let fresh air enter. Maintain the room temperature at 75 °F. or more.
Turn the eggs at least two or three times daily during the first 18 days of incubation. Turning keeps the embryo from sticking to the shell membranes when left in one position too long. DO NOT turn eggs during the last three days before hatching. The embryos are moving into hatching position and do not need to be turned.
An excellent method to tell if all eggs have been turned is to mark an "X" on one side of the shell and an "O" on the opposite side. You can always tell if the eggs have been turned by noting which side is up. Write the marks with a pencil so harmful chemicals do not enter the eggs. When turning, be sure your hands are clean and free of greasy or dusty substances. During the first week in incubation, turn eggs carefully because the developing embryos have delicate blood vessels that may be ruptured if jarred or shaken.
Mark eggs incubated on different days with the date you placed them in the incubator. This prevents eggs from being overlooked and left in the incubator after they should have hatched. The eggs should be set and maintained vertically with the large end up or horizontally with the large end slightly elevated. This will let the embryo stay in the proper position for hatching.
Chicken eggs require 21 days to hatch, but the incubation periods for the eggs of other species of poultry vary. The approximate periods of incubation required for various species of poultry and game birds are as follows:
http://www.poultryhelp.com/avianembryo.html
