Egg Incubation Guide
When incubating eggs, there are five key factors to bear in mind:
1. Temperature With the egg at the correct temperature (for most species this is 37.5°C), the biological process of incubation will commence and the embryo will begin to grow. The temperature must be sustained throughout the incubation period.
2. Egg turning and positioning As the egg is turned, the embryo will pass through the egg white, allowing it to gain fresh nutrients. As the embryo grows, correct positioning of the egg ensures that the embryo forms in the correct position for hatching. 3. Humidity The shell of an egg is porous, meaning that water can pass through it. Over the egg incubation period, water passes from the egg to the air outside. Correct humidity ensures that the right amount of water is lost over time. It is important to remember that humidity will vary, and this is not a big problem; it is the average humidity that matters more. 4. Fresh Air It is important to note that during incubation the egg breaths; it takes in oxygen from the surrounding air and gives out carbon dioxide. A fresh air supply is vital to egg incubation and hatching eggs. 5. Clean Environment During incubation, eggs are susceptible to infection. The warm, egg incubator is a perfect breeding ground for bacteria. Eggs should be clean and disinfected before egg incubation begins.
Egg Collection, Storage and Handling
Egg Collection It is best practice to collect the eggs before 9am and to check back at midday in case the hen has laid any more. However, the more frequently eggs can be collected; the less chance there is of them becoming soiled or dirty. Eggs that are left in the nest for more than 24 hours tend to result in poor hatch rates. Eggs are usually collected in a basket or rubber bucket. It is very important that eggs are handled carefully to avoid them getting jarred or cracked. Many people add an extra layer of kitchen roll or wood shavings into their basket for increased security. It is also important to wash ones hands before collecting the eggs. Your hands are the perfect breeding ground for bacteria and this can easily be spread to the eggs. If your hands are sweaty or greasy, this can pass onto the eggs; blocking their pores and preventing respiration and moisture loss – all of which can affect the chances of a hatch. Before collecting the eggs, wash your hands carefully with anti-bacterial soap or incubation disinfectant. Rubber gloves can also prevent the spread of germs and bacteria.
Egg Storage Egg storage is an optional step before egg incubation. Many breeders prefer to build up a “batch” of fertile eggs before commencing egg incubation. The duration for which to store your eggs is completely up to you. However, it is not recommended to keep your eggs any longer than 10 days before incubation. Cleanliness During storage, it is very important that you ensure the quality of your eggs. Cracked, misshapen or heavily soiled eggs should be discarded to avoid contamination. Some slightly dirty or soiled eggs can be washed with incubation disinfectant. When washing eggs, make sure that the water or solution you use to clean the eggs is significantly warmer than the egg temperature; this will cause any bacteria to be drawn away from the pores. Washing your eggs is highly recommended. However it is important to note that this process will remove the egg’s natural, thin outer coating. This will leave the egg vulnerable to future infection so it is vital a high level of cleanliness is maintained throughout the egg incubation period.
Storage Temperature & Humidity When storing eggs it is recommended to keep them at a room temperature of between 15°C and 18°C. Cool, draft free locations are ideal places to store your eggs. Before incubation, eggs should be brought steadily up to room temperature. This avoids drastic temperature changes and “thermal shock” to the egg. As for humidity, lower is better, but not essential. Some breeders recommend a humidity level of between 45% and 55% RH; this is ideal, however, unless you plan to incubate eggs on a large scale, you are not likely to witness any difference.
Egg Turning During Storage During storage, eggs should be turned a minimum of once a day; two or three times per day is much better. When turning eggs, try to make sure each egg is turned 45 degrees each way, totaling 90° over the course of a day. Turning the egg during storage ensures the eggs outer membrane does not stick to the shell. The method you use to turn your eggs is up to you. Some people prefer to turn their eggs manually by hand, whereas some prefer to place their eggs pointy side down in an egg box at an angle, and change the angle of the egg box two or three times a day. However a growing number of people use their egg incubators to turn their eggs before incubation. This can be achieved simply by using removable automatic egg trays, or by placing the eggs in the bottom of a rocking incubator with just the rocking motor on.
Egg Handling Tips Eggs should always be handled with the upmost care. Severe bumps may rupture the egg’s internal membrane, even if the egg shell appears undamaged. Care must still be taken when handling eggs in the incubation stage. A severe bump can rupture blood vessels; causing the chick to bleed to death. If eggs have endured a lot of handling, perhaps from being sent in the post, it is important to set them pointy side down for at least 24 hours before incubation. This will allow the contents of the egg to settle.
The Egg Incubation Process
Stage 1 (Fertilization) The yolk is dropped from the ovary and fertilized by the male sperm. The fertilized yolk then travels down the egg canal and receives several coatings of albumen (egg white). The shell is then developed in the hen’s shell gland. This process takes approximately 20 hours; after which, the egg is laid.
Stage 2 (Days 1 and 2) The egg is hatched and gradually cools. At this stage, embryonic growth slows and often stops. Many birds will develop a “clutch” of eggs that they wish to incubate. The clutch size depends on a variance of factors including hereditary traits and environmental factors. For artificial incubation, the breeder can actively choose the clutch size they wish to incubate. He or she may choose to store the eggs at room temperature (15-18°C) for up to 10 days in order to gather the required amount of eggs. On the first day of incubation, embryonic growth begins again and the cells begin to divide and multiply rapidly. By the end of day one, the head, eyes, nervous system and circulatory system have begun to form. The heart is formed on day two and is functioning within 48 hours of incubation.
Stage 3 (Days 3 and 4) On day three, the heart develops from its simple form to become a fully functioning, beating heart. Additional membranes are formed in this time. This creates the amniotic sack which the embryo will float in for the duration of incubation. Within the amniotic sack; amniotic fluid, combined with correct egg turning, ensure the embryo orients itself correctly during hatching. Although the heart is still positioned outside the body, by the end of day four, the legs and wing buds have begun to form. Stage 4 (Days 5 – 10) By the end of day six, the legs and wings are nearly complete. Feathers begin to appear at day eight, and by the end of day nine the embryo is beginning to look like a chick - the chicks heart is now in place within the body. By day ten, the bones are beginning to form.
Stage 5 (Days 11 – 21) By day thirteen, the chick’s down feathers are fully formed and present on most of the chick’s body. The legs and wings are also complete with bones and muscle tissue. By day sixteen, the beak, leg scales and claws are very nearly complete. The remaining yolk then becomes a food source for the developing chick; this is used up by day nineteen. At day nineteen, the chick is beginning to struggle to get enough oxygen to its blood; carbon dioxide levels in the chick’s blood begin to rise dramatically. A rise in the carbon dioxide level within the chick’s blood causes the chick’s neck to twitch; its beak is forced through the membrane sack into the air sack at the blunt end of the egg. The beak then opens for the first time and the lungs inflate; fresh oxygenated blood is then circulated around the body. At this point in the incubation period, the chick is under significant stress; many chicks die at this stage of incubation because they are too weak or undernourished to deal with the stress they are under.
Stage 6 – Pipping (Day 20) A day or so before hatching, the chick begins to “chirp”. Chirping is the sound made by the chick in an effort to communicate with its mother. The mother then naturally chirps back encouragement. In artificial incubation, some breeders enjoy chirping back to the chick to encourage it to hatch. The chick continues to breathe from the air sack but soon begins to run out of air. This again begins to cause the chick’s neck to twitch involuntarily. At this stage the chick’s beak begins to penetrate the outer shell; this is known as “pipping”. The chick’s legs begin to move and twitch which causes the chick to move around inside the egg and the hole gets bigger. After an initial hole has been made, it is likely that the chick will pause (sometimes for up to 24 hours) to regain some strength and energy. By the time pipping begins, egg turning should have ceased. This is very important as on day twenty, the chick gets itself into its ideal hatching position inside the egg; egg turning at this point would completely disorientate the chick and may result in injury or death.
Stage 7 – Hatching (Day 21) On day 21, the chick will make a determined effort to chip off the top at the pointy end of the egg. The chick takes its first gasp of air as the top of the egg is released. It will usually rest for a while here, but will then go on to shake off the bottom half of the shell. The hatching process takes time and the chick is visibly exhausted after its ordeal. When the chick hatches it is likely to be wet, but all the yolk should be absorbed into the chick’s stomach. If there are any large pieces of yolk attached to the chick’s bottom that were not absorbed into its stomach, the chick has a hernia and unfortunately will not survive. The newly hatched chicks will stagger clumsily around the incubator or nest stopping for frequent rests. Do not worry; it is often the case that some chicks appear very tired and unwell after they have first hatch. But after a short rest, chicks are very likely to spring back to life at the first sign of a stimulus. Never turn off the incubator too early. Some eggs will naturally hatch later than others. Leave the un-hatched eggs in the incubator for at least another 24 hours after the expected hatch day; you never know, they may just surprise you. Remember to resist the temptation to keep opening the incubator. Chicks are very sensitive to the cold and, by opening the incubator lid, valuable heat energy is lost. Chicks will happily remain in the incubator for 48 hours after hatching. They will not need any additional food and water during this time, as they will have enough food remaining in their bodies from their time inside the egg.
Incubation process Troubleshooting
Problem Possible Causes Chicks hatch late
• Large Eggs • Old Breeding Stock • Eggs have been stored for too long
Weak embryos
• Inbreeding • Incubator Humidity too high Slow (drawn-out) hatch
• Mix of eggs (different sizes, different aged breeding stock, different storage times) • Poor egg handling • Hot or cold spots in the incubator • Incubator or Hatcher temperature too high or low
Sticky Chicks, smeared with Albumen (Egg white)
• Low incubation temperature • High incubation humidity • Poor egg turning • Old eggs • Very large eggs
Chicks stuck in shell, dry, shell fragment stuck to feathers
• Low humidity in storage • Poor egg turning • Cracked shell or poor shell quality
Premature hatching, bloody navels
• Temperature too high
Small chicks
• Small eggs
• Low humidity • High temperature • High altitude • Thin, porous shells
Unhealed naval, dry, rough down feathers
• High incubator temperature or temperature fluctuations • Humidity too high when hatching • Inadequate nutrition
Weak Chicks
• High hatching temperature • Poor hatcher ventilation • Contamination
Chicks malpositioned
• Eggs sat small end up position • Inadequate turning • Excessive turning at late stages • Too high or too low temperature • High humidity • Old breeders • Round shaped eggs • Nutritional deficiencies • Retarded development • Poor egg handling or storage conditions
Malformations
• Poor storage conditions • Jarring of eggs • Nutritional deficiencies • Inadequate turning • High or low temperature • Inadequate ventilation
Crooked toes, bent legs
• High or low temperature • Poor nutrition (especially vitamin B)
Short down, wiry down
• Nutritional deficiencies (especially riboflavin) • High incubation temperature
Eyes closed, down stuck to eyes
• Temperature too high in hatcher • Chicks remain in hatcher too long after hatching • Excessive air movement in hatcher
Exploding eggs
• Dirty eggs from nest • Eggs not washed properly • Water condensation on eggs • Water sprayed on eggs • Contamination from earlier exploders • Contaminations from handling with dirty hands
Dwarf embryos, runts in growing chicks
• Egg contaminations • Breeder diseases • Nutritional deficiencies
Hemorrhage
• Incubator or hatcher temperature too high • Rough handling at transfer • Nutritional deficiencies (vitamin K or E) • Contamination
Swollen head and back of neck
• Nutritional deficiencies
Small air cell, egg weight loss under 10%
• High humidity • Very thick shells • Low temperature
Exposed brain
• High incubation temperature • Low oxygen levels
