Why do incubators turn eggs.

One of my incubators showing eggs in a cradle

Incubators are designed to do the same job as a mother hen and turn eggs either continuously, or on a pre set cycle.

It is important to turn the eggs at least three and preferably five times daily as this most closely mimics the way hens treat their eggs in the nest. Turning the eggs is important for gaseous exchange (breathing) and to stop the membranes sticking together inside the egg. Not turning the eggs means the embryo might not be able to move itself into it's final hatching position and may never emerge from the egg.

You should always mark eggs you have selected for incubation with a pencil or water based marker so as you know which side up they are. Some people use a cross on one side and a circle on the other but there are many ways. It also helps to keep a pen and paper handy and note the day and time you turn your eggs so as you know where you are in the cycle.

Below: Empty incubator showing egg rolling cradle.

If you have forgotten to turn eggs in incubator then just start again as soon as you remember. Turn them a little more often for the next day or so and make sure they are the opposite side up overnight to give them the best chance.

If you are ever unsure about how to treat eggs in an incubator, think what a mother hen would do as she sits on her nest.

Should you turn eggs before you put them in the incubator?

Egg that are to be stored for more than 24 hours before incubation need to be turned at least once a day.

This is not as important, if you think about how a hen would do it, she would only start turning eggs in a nest after she began to sit on them, which could mean they have spent 10 to 12 days lying on their sides with no real problems.

Why do you have to turn eggs in a incubator?

Egg turning stimulates the development of parts of the egg and stops the membranes sticking together. The yolks contains fats and so will float in the white, and over time and the yolk will stick to the top of the egg if not moved around regularly.

  • Stimulates growth.
  • Stops membranes sticking.
  • Evens out the temperature inside the eggs.
  • Helps with gaseous exchange (breathing).

Turning is very important for the rate of development of the area vasculosa or the membrane which grows around the yolk and is rich in blood vessels. The area vasculosa is important for sub-embryonic fluid formation, as well as for yolk uptake later in incubation.

Do eggs have to be turned during incubation?


All birds eggs have to be turned during incubation.

Eggs must be turned at least 3-5 times daily during the incubation period or moved by the automatic egg roller continuously. The reason for the odd number of egg rotations every day is to change the side of the egg that spend the long night the same way up.

If you were to only turn eggs two or four times a day then the same side of the egg would face the top for the long overnight session which may impact your hatch rate.

Do not turn eggs during the last three days before hatching. The embryos are moving into hatching position and need no turning.

Is automatic or manual egg turning best?

Automatic egg turners are the best as you don't need to remember to turn the eggs andfthey work overnight.

Automatic egg turners are the best by far as most move the eggs continuously backwards and forwards on a two hour cycle. This enables you to keep the incubator closed during incubation to maintain proper temperature and humidity.

Below: An incubator with a cradle type egg turner and a small motor to push the eggs backwards and forwards.

Just remember to turn the egg rollers off otherwise you could end up with hatched chicks being rolled about your incubator, and yes, I have done this on more than one occasion in the past and it reduced my hatch rate by around a third.

The second best turner is the one that manually turns all the eggs at once but has a handle outside the machine.

How do egg turners work?

Egg turners work in four ways:

  1. The eggs sit on rollers which turn slowly.
  2. The eggs sit in a cradle that rocks them backwards and forwards.
  3. The eggs sit in a grid that moves back and forth over a solid base.
  4. The whole incubator rocks from side to side.

The eggs are turned continuously or in cycles triggered by the software that controls the manchine. Some of the work very slowly and all the time and other work in bursts, turning all the eggs at once.

Below: Some incubators tilt the whole machine from side to side to turn eggs.

Neither method is better, they both accomplish the task.

Will eggs hatch if not turned?

It is unlikely that eggs will hatch without incident if they are not turned every day. I have had incubators where the egg roller has failed on day 10 during the cycle and nothing as hatched at all even though most of the eggs continued to develop.

Not turning the eggs for 7 days resulted in 100% loss.

How to turn eggs in incubator:

To turn eggs by hand, first make sure you have washed your hands, then open the incubator and carefully roll the eggs over by 180 degrees. Work quickly and with care not to drop any of the eggs.

Below: Remember to remove egg cradles for the hatch as the hatch will be better if the eggs are on their sides.

If you have an automatic turning incubator, you should still mark the eggs so you know it is working properly and check a few times a week. If it has a seperate turning mechanism, remember to turn it on and set the days correctly if you have a programmable machine.