Incubators & Hatchers

What is an Incubator and Hatcher?

Basically, an incubator is a large box with a controlled environment specific for a certain bird egg types to grow. A very large hen if you will. A hen’s body temperature runs around 104 – 105ºF (@40ºC). An incubator has an internal temperature of 99.5ºF (37.5ºC). So, they are very close. The following table provides the recommended temperatures and humidity settings for chicken type eggs:

Incubator / Hatcher Stats

Eggs are set in the incubator and monitored for 18 days. After 18 days, they are transferred to a hatcher where the temperature is 1º less than the setter and the humidity is also lower. After 18 days, the chick has pretty much absorbed the yolk and egg white and doesn’t require turning.

The temperature in the hatcher is lower because the chicks produce more body heat and will raise the temperature naturally. Also, the wet-bulb humidity is lower just to provide enough ambient humidity to prevent chicks from sticking to their shells when they pip out. Eventually, when many chicks start to hatch, the humidity will rise naturally. Sometimes it might even reach 90ºF wet-bulb.

If you are using a small incubator / hatcher which only holds one setting at a time, after 18 days, you will want to reduce the temperature and humidity and set the egg flats straight or flat without turning. Some small setters require the egg trays to be removed from the turning rack and placed on the bottom of the setter.

It also very important to have a proper air exchange flow throughout the setters and hatchers. This is basically a ventilation system that removes air out the back thus renewing it through the front of the machine. Some small incubators use a small exhaust fan for this function. At industry level, there are large ducts which suck air about the back pulling fresh air through the front vents.

Incubator Air Flow

Here is an incubator made more for home use:

Home Incubator

One thing about this design, is that you have to turn each egg individually. I would prefer a system where it is easier to turn all eggs at the same time. To do this, you can incorporate a small portion of a cardboard filler flat and a slanted surface which is approximately 45º.

45° angle

So, if we combine both the incubator and the turning rack, it would look something like this:

Home Incubator with turning rack

Egg Turning

Egg turning during the incubation period is very important. Even in the wild or range reared hens, turning occurs. You will notice the hen sitting on the eggs and every now and then she will stand up and move the eggs with her beak rolling them over into a different position. The commercial incubators do this with a turning mechanism which turns the eggs 90º every hour.

In a homemade incubator, you will most likely have to turn the eggs yourself. It won’t be necessary to turn them every hour, but at least 4-6 times per day. If you look at the diagram above, the eggs can be turned very easily and quickly. All you would have to do is change the triangle to the other side and make sure the eggs are actually in the same position as before:

Turning Position

Always remember that when you incubate eggs in flats, that the pointed part of the egg faces down. The reason for this is that an egg’s air cell is positioned at the large end of the egg and when the chick forms and is ready to pip the inner shell membranes to take its first breath which it assumes is upwards, it won’t find it and drown.

Proper Egg Position

Humidity in Incubator (setter)

The amount of humidity inside the incubator or setter is very important. It is this percent relative humidity that allows for a slow and controlled dehydration of the egg.

If the humidity is too high, the egg will not lose enough water and the chick could die. If the humidity is to low, the egg can experience an excess of water loss and thus dehydrate and kill the chick. If the chick hatches from a dehydrated egg, it will be small and weak.

What is the proper humidity percentage supposed to be? As a rule of thumb, it should be around 55% relative humidity of 83-85ºF wet bulb. Note that if your temperature is low, the humidity might not rise to its appropriate level.

There might be several factors which could affect the percent humidity in a machine. For example, large eggs have larger pores thus would require a slightly higher humidity to avoid excess dehydration. Smaller eggs have smaller pores thus needing a lower humidity setting.

There is a way to check this through egg candling. This is when you shine a bright light through the large end of the egg and see how large the egg’s air cell has become. The following is a guide to how large it should be:

Air cell size

Temperature in Incubator (setter)

The temperature in the setter is pretty much standard for chicken type birds, 99.5ºF (37.5ºC). If you have a multistage setter (takes several settings at different times), then you might want to slightly increase thistemperature to 99.7ºF (37.6ºC) for the first setting or two, then drop it down to 99.5ºF. This will compensate for the machine being empty. If you have a single stage setter (only takes one setting) then you might want to increase to 99.7ºF for the first two – three days and then drop it to 99.5ºF.

Time of Incubation

For chicken type birds, it takes roughly between 20.5 – 21 days for the chicks to hatch. Some external factors such as heat can influence this time period.

If the machine or ambient temperature around the machine is too hot, it is likely that the chicks will hatch earlier. Be careful as excess heat in the setter can kill or cause deformed chicks.

If the temperature in the setter is low, the chicks will take longer to hatch. This can also produce weak chicks.

It is important to try and keep the temperature both inside and outside of the setter as close to the recommended as possible. You might want to place you setter in a controlled environment.

Egg Trasnfer

After 18 days (for chicken type birds) the eggs should be transferred to the hatcher. Normally this is a separate machine where the conditions are slightly different from the incubator.

The hatcher’s temperature is 1º lower than the setter (98.5ºF / 36.9ºC). There is no turning and the humidity is set to around 83ºF wet bulb reading.

When the chicks start to hatch, the humidity will rise by itself due to the wet chicks. After a while it will start to drop again.

If you are using a home based incubator, where the chicks are incubated and hatch in the same machine, then you must modify the temperature and humidity inside the machine. If you used the 45º inclined rack for egg tuning, remember to remove the eggs from the flats and lay them down on the floor of the setter.

Trouble Shooting your Hatch

It is common practice in large hatcheries to perform egg candling and embryo diagnostics.

The first allows us to test the humidity and also check for infertile egg count. A clear egg will shine like a light bulb when you shine a light through it. This also indicates where there might be problems affecting the hatchability. This is normally done at 10 days of incubation.

A high clear egg count could mean a male problem or feed problem or even a transportation problem is at hand.

The embryo diagnostics, or egg breakout, is done after the hatch where a sample of unhatched eggs are gathered, marked by incubator and hatcher number and by flock. They are then opened to see why they didn’t hatch.

The results of the break out are written down on a table.

Egg Breakout Table

Sample: is just the amount of eggs per machine/flock you are going to break open.

Infertility: This is when the egg was being formed in the hen’s oviduct, it never got fertilized. This could be a male or feed problem on the farm.

Infertile Egg

Phase I (1-7): This phase covers the first 7 days of the egg after being laid. If you find many eggs in this phase, there could be a problem with egg handling. This could include anything from improper storage temperatures, rough egg transportation, strong temperature changes, feed inefficiencies, and others. Problems in this phase normally has to do with the farm.

In this phase we also start to see blood vessels, heart beats, beak and wattle formation.

Ebrionic Development Phase I

Phase II (8-14): In this phase, the eggs have been in the incubator from 8 to 14 days. Chick embryo development is far along. If you see that many of the unhatched eggs have embryos in this stage, there is most likely a problem with the incubator. Possibilities are improper turning, temperature, humidity, ventilation, inverted eggs (pointing upwards), rough egg handling or toxins in the feed.

Embryonic Development Phase II

Phase III (15-21): This is the final stage of embryo development. At this point the embryo has already turned its head towards the large end of the egg. If you find unhatched eggs in this time frame, it could be due to improper temperatures, improper humidity, turning, ventilation, rough
handling at transfer, wet trays at transfer, contamination, feed inefficiencies, inverted eggs and others.

Embryonic Development Phase III

This tool is mainly used when you have a bad hatch. If 8 out of 10 eggs hatched, don’t worry about it, now if only 4 or 5 hatched, break open the unhatched eggs and see why they didn’t hatch.

Most problems have to do with storage, storage temperature, improper setter temperature and/or humidity. Turning can be a factor so be sure to turn your eggs on a regular basis.

Make sure that internal and external temperatures are stable. Do not let the setter or hatcher get too hot or too cold, this will definitely alter your hatchability. If your thermostat isn’t too accurate, see if you can set it to oscillate between 99.3 and 99.6ºF.

If you have eggs from a young hen or flock (small eggs), then you can use a lower humidity setting (50% RH) to ensure that the proper amount of fluid is lost from the egg before hatching. For older flocks (large eggs), you will want to use a higher setting (55% RH).

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