Incubation and Troubleshooting

Storing Eggs

Eggs should be incubated within one week to 10 days after they are laid. Hatchability declines rapidly when incubation is postponed for more than 10 days. Store eggs in cartons or cases large end up at 40 to 70 degrees F (50 to 60 degrees F is best) with a relative humidity of about 75 percent. If the eggs are stored for more than two to three days before incubation, turn them each day so the yolks won't stick to the shells. Begin by propping up one end of the case or carton; each day, change the position of the block, or turn the container end for end. It is a good idea to warm up the eggs to room temperature before putting them in the incubator.  

Location of Incubator

To keep a constant temperature, place the incubator where it will receive as little temperature changes as possible. Do not place it near a window where it will get direct sunlight. The sun's heat can raise the temperature high enough to kill the developing embryos. Connect the unit to a dependable electrical source, and make sure the plug cannot be accidentally unplugged.  

Preparing the Incubator

Before you incubate, be sure the incubator is working right and that you know how to operate it. Place warm water in the humidity pan, and adjust the heat source until the incubator temperature stays at 99.5 (fan forced) or 101 (still air) degrees Fahrenheit. Check the thermometer often for at least 24 hours before you incubate to be sure it will stay at the correct temperature. Heat sources with a thermostat are most reliable. Light bulbs without a thermostat can be difficult to control unless the room temperature is fairly constant.  

Incubator Operation

Keep the temperature at 99.5 (fan forced) or 101 (still air) degrees Fahrenheit. Place the thermometer at a level or slightly above, where the center of the egg will be. Overheating the embryo is much more damaging than underheating it; overheating speeds up embryo development, lowers the percentage of hatchability and causes abnormal embryos. Although a short cooling period may not be harmful, long periods of low temperatures will slow embryo growth. Very low temperatures will kill the embryos. Avoid incubator temperature variations of more than .5 degree. Fewer eggs will hatch if the temperature is either too high or too low for several days. The moisture level (humidity) in the incubator should be about a 50 to 55 percent relative humidity, with an increase to about 65 percent for the last three days of the incubation. Moisture is provided by a pan of water under the egg tray. Add warm water to the pan as needed. To boost humidity, increase the size of the pan or add a wet sponge. You can also adjust the humidity by adding or cutting back on airflow.

Use a wet bulb thermometer to determine relative humidity with help from this chart:

If you don't have a wet bulb thermometer, you can check humidity by noting the size of the air cell in each egg. The air cell grows during incubation at a certain rate based on temperature and humidity. Ventilation is adjusted by opening or closing the vents on the sides or top of the incubator. Normal air exchange is needed during embryo development. The embryo needs oxygen and produces carbon dioxide. You'll need more airflow as the chicks begin to hatch. However, you should maintain correct relative humidity until most of the chicks are out of their shells. Do not open the incubator unless necessary during the last three days of incubation. The eggs should be placed in the incubator on their sides. Turn them at least three times a day, except for the last three days, when they don't need turning. Turn the eggs an odd number of times so the position that is up the longest (at night) will be changed from day to day. Mark the date or an "X" on each egg so you can tell if the eggs have been turned. When you turn the eggs, move them to a different part of the tray to protect them from temperature variation. If the eggs are not placed on their sides, they should be placed at an angle so the small ends are in the downward position.

Candling the Eggs

"Candling" is when you check the egg contents using a shielded light in a darkened area. If you find eggs that don't have proper embryo development during candling, remove them. These eggs will rot quickly and may explode in the incubator. You can also check air size and determine incubator humidity by candling. You can make an egg candler from a wood or metal box, or a container, in which you mount a 60-watt light bulb. Make a one-inch hole in the end near the bulb. For better viewing, place a felt or cloth cushion around the opening so an egg fits the opening better and light does not leak around the egg. Hold the large end of the egg up to the candling light. You won't see much development until the fourth of fifth day of incubation. You'll see embryos more easily in white or light-colored eggs. The contents of the egg have a pinkish color or cast when the embryo is developing properly as the embryo grows, it will take up more space within the shell. Toward the end of incubation, the contents will appear dark except for the air cell. Eggs that are clear four or five days after incubation or show little development at 10 days should be removed from the incubator. They are infertile or contain dead embryos. Candling will not hurt embryo development or hatching time if you handle the eggs gently. Remove the eggs from the incubator only a few times and don't allow them to cool.

Getting Ready for the Hatch

When you turn the eggs the last time, three days before hatching, place a layer of crinoline or cheesecloth on the screen under the eggs. This will make cleaning the incubator easier after hatching. Most chicks should hatch within a 24-hour period. Late-hatching chicks may lack vigor or be abnormal. After the chicks are dry and fluffy, they can be removed from the incubator. Or you can lower the incubator temperature to about 95 degrees F if you plan to keep the chicks in the incubator for one or two days. Clean the incubator after the chicks hatch, so it will be ready for the next time. Sanitation is an important part of incubation. Throw out the crinoline or cheesecloth, along with the shells and other remains. Clean the inside of the incubator with soap and water, and let it dry before storage.

This page was compiled primarily from information received from an article written By Mahmoud El-Begearmi and the University of Maine Cooperative Extension.