Incubating and hatching eggs is one of the most enjoyable (and addictive) aspects of chicken keeping. Nothing beats watching those little ones fight their way out of the eggs, after the 3 weeks of fretting and fussing and watching the incubator, wondering what is going on in there. To get you started on this wonderful journey, here is a quick rundown on...
Incubating Eggs 101
First things first—chicken eggs should hatch in 21 days, though some may hatch a day or two early and some a day or two late after the incubation period began. A "day" is counted as a full 24 hours, so day one would be the first 24 hours after setting the egg. Day two the next 24 hours, etc. If you set eggs on a Monday, it's usually a safe bet that they will hatch on a Monday, three weeks later.
Select clean, even shaped, undamaged eggs for incubating. It's best not to wash the eggs prior to setting, as washing can remove the protective "bloom" on the shell and make the eggs more susceptible to absorbing bacteria and other nasties, which could compromise your hatch. If possible, do not store them too long pre-incubation. Ideally eggs should be set within a week after being laid and after 10 days the hatchability of the eggs drops significantly. Store the eggs in a cool place (NOT the fridge) and turn them once a day to keep the yolks centred.
**A note on shipped eggs: shipped eggs should be allowed to rest for 24 hours prior to setting, to allow the contents of the eggs to settle. Place shipped eggs upright, with the fat end of the egg up, in an egg carton, or something similar. Shipped eggs often have loose or damaged air cells and should ideally be incubated upright, with the fat end up. For more information and tips on managing these see here.
Before putting your eggs into an incubator, plug it in and make sure the temperature is steady. In a forced air incubator (with a fan) the temperature should be 99.5–100*F. In a still air incubator the temperature should be slightly higher, 101–102*F measured at the top of the eggs. I use a thermometer and a hygrometer (which measures humidity) in my incubator. Hygrometers can be purchased quite cheaply at a cigar shop, Radio Shack and I believe even Walmart. You want 28–50% humidity for day 1–18, depending on air cell size, then 65% to 75% for the last few days.
During the first 18 days of incubation, the eggs should be turned a minimum of 3 times a day. Use a non-toxic marker and mark eggs with an X on one side and an O on the other so when you are turning them you can make sure they all got turned. More about turning later...
There are many makes and models of incubators for sale and they vary greatly in price, quality and user-friendliness. It's recommended that you read our Egg Incubator Reviews and get some opinions before you choose one! If you are the DIY type, building your own incubator is fairly easy too. Our members have shared designs, plans and ideas on their homemade incubators HERE,
Natural fertility may vary from 55% to 95% with season, depending on condition and age of your birds. You might be safe to expect that 50% to 75% of the fertile eggs will hatch, though 90%-100% hatches can and does happen. With shipped eggs the hatch rate is approximately 50% overall. After 5–7 days of incubation, white-shelled eggs can be candled to see if embryos are developing. Candling is done by going into a dark room/area and shining a bright light (usually a flashlight) into the egg to see what is going on inside.
Fertility and embryo development is usually apparent by day 5–6, when infertile, developing eggs, some veins and a small embryo can be seen inside the egg. If there is no sign of development by day 10, you may discard any "clears". However, sometimes embryos are hard to spot, so some hatchers wait until around day 14 or so, before discarding any undeveloped eggs. When candling, also check for blood rings (showing as a dark ring around the inside of the egg, along the shell, usually roughly in the middle of the egg, and other signs of problems. See here for egg candling pictures.
Soon after an egg is laid, a small air bubble starts forming in the large end under the shell. This air sac serves as a "breathing space" for the hatching chick to pip into in order to breathe, during the hatching process. This is known as an "internal pip". The drier the outside air is, the more fluid is depleted from the egg contents and the faster the bubble grows. Correct humidity in the incubator insures that the bubble does not grow too big, depleting essential fluids, or deny the chick enough air by remaining too small.
The importance of correct humidity is more apparent at the end of incubation. The normal condition is that the air cell has enlarged to the point where the chick can reach his beak through the membrane wall, allowing it to breathe, before it pips through the shell, after which it will "zip" around the shell. If humidity has been excessive, the chick may pip internally into the air cell and drown in excess fluid. On the other hand, if humidity has been too low, the air cell will be oversized and the chick may be unable to hatch.
A rough guide showing the development of the air cell on different days of incubation
Positioning of the Eggs
An incubating egg could set in a normal position as it would on a flat surface; that is with the large end slightly higher than the point, or upright in egg cartons/turners, with the fat end of the egg always up. An egg that persistently has the small end elevated may cause the embryo to be misoriented with the head toward the small end. In the misoriented position, the chick is likely to drown on pipping. Therefore, it is quite important that in general, the large end of eggs should be slightly higher than the small ends; or as they would lie naturally on a flat surface.
Turning is essential during the first 14 days of incubation, but most people continue it to day 18. Turning is stopped during the last 3 days. If hand turning, always turn the eggs an uneven number of (minimum 3) times a day, so the eggs do not spend two nights in a row in the same position. If not turned to a fresh position frequently during the early stages, the developing embryo touches the shell membrane and sticks to it causing abnormal growth. Turning the egg aids these movements within the egg, and mimics what a mother hen would do naturally.
The last few days of incubation, days 18–21, are known as "lockdown". When lockdown day comes, switch off/remove turners (if present), increase the humidity in the incubator to around 70% and maintain it. Do not open the incubator unless necessary and do not turn the eggs during this period.
What to do When when the Chicks Hatched
After the chick hatched allow it to dry off and fluff up in the incubator before removing it to a brooder. Newly hatched chicks can survive for up to 3 days on the yolk they absorb during the hatching process, but once you put them in the brooder make sure there is at least water available and offer them food after a day or 2. For more on raising chicks, see HERE.
Feed and water must be available at all times from the time they are out of the incubator. Do not dole out a measured daily ration. Do not let feed or water run out! Chicks need to be fed a chick starter. Medicated chick starter can be fed to help prevent Coccidiosis. Please note: chicks fed a medicated starter may still get coccidiosis. The medicine in the feed only help prevent it!
Prevent Accidental Drowning
Water receptacles are a risk with baby birds during their first week. Chicks are clumsy and can easily fall into water dishes and get drenched or even drown. A common device to prevent drowning is to use a shallow water cup with marbles or small, clean pebbles set in the water over the entire drinking area. The chicks will drink in the spaces between the marbles/pebbles.
Further Recommended Reading:
—Incubating & Hatching Eggs Forum Section
—The Beginner's Guide to Incubation
—Development of a Chicken Embryo Day by Day
—Guide to Assisted Hatching for All Poultry
—Step by Step Guide to Assisted Hatching
—Egg failure to hatch - Diagnosing incubation problems
—Diagnosing causes of malpositions and deformities in chick embryos
—Diagnosing hatch failures - It starts with the egg