Basics of Chicken Egg Incubation: What You Need To Know

Over the last couple of years, the affectionate term “chicken math” has been coined. This is a funny term created by chicken keepers, for chicken keepers.  The answer/justification to the age-old question, “How many chickens do you have?” – Chicken math.

Nothing contributes to “chicken math” faster than hatching your own chicks. Whether it is from a broody hen or an incubator in 21 days, new baby chicks can be yours. For myself, the start of my own chicken math adventure was with a pullet chick that ended up being a rooster, his name was Roger. I decided since we had a rooster, there was no need to buy chicks anymore, we could just get an incubator and hatch our own. This simple experiment is what led to me eventually hatching thousands of chicks. Here are some things I wish I would have known starting out.

Basic chicken incubation fast facts:

• Chicken eggs take 21 days to hatch (other fowl have variations in incubation time, quail, turkey, duck, etc). This article is based on chicken eggs. 
• Eggs have to be incubated within the first 7 days of being laid for best results. 
• Do not wash eggs that you want to incubate since they have a protective coating that protects them called the bloom. If the egg is very dirty, do not risk incubating it. The feces and dirt on the egg can grow bacteria when put into a warm and moist incubator. You can risk the whole batch of eggs. 
• Candling involves using a bright light to look into the egg to monitor the growth of the embryos. This is a unique experience and useful to learn. 
• There are two phases of incubation: development (the first 18 days) and lockdown/hatching (the last 3 days).
• Be prepared for rooster chicks! Since there is no way to sex eggs for incubation, have a plan for the rooster chicks that you will ultimately hatch. Just like any other animal, there is a 50/50 chance that each egg will produce a pullet or rooster.

Now to the more technical side of chicken incubation when using an incubator. Not all incubators are created equal. Some are much more consistent and easier to use than others. There are machines that are completely automatic and some that have to be manually adjusted. I will add some troubleshooting to each section to help you with any issues that may occur. 

1) Temperature

The eggs need a consistent temperature of 99.6-100.0 to develop. A secondary thermometer is highly recommended to monitor the temperature closely. The settings on the incubator can sometimes be wrong and need to be adjusted accordingly.

Troubleshooting:

If the temperature is too low: the development can stop or be delayed (chicks hatching after 21 days), the chicks can have deformities, hatch rates can be low, or the chicks can be weak.

If the temperature is too high: the development of the embryo can be accelerated leading to deformities or early hatching (chicks hatching before 21 days) of potentially weak chicks. High temperature can also cause the egg to dehydrate by taking too much moisture from the egg leading to poor hatch rates. 

2) Humidity 

This is a tough one. Everyone has their own theory on what the optimal humidity should be for hatching, and it can vary depending on the climate and elevation where you live. Talk to other people incubating in your area and see what is working for them. My personal preference is ~40% for the first 18 days of development and then bump the eggs to 65% for lockdown. Some incubators have automatic humidity control which is great if you want to just fill the water reservoir once a week or so, versus adding water daily. A separate hygrometer is highly recommended to monitor humidity closely.

Troubleshooting:

Too high: If the humidity is too high during the development phase, the air cell cannot form properly because not enough moisture is released from the egg. Inadvertently “drowning” the chicks during hatching can occur since the air cells will not be big enough for them to breathe. Poor hatch rates are associated with this, and most of the time, the chicks are fully formed but do not hatch.

Too low: Too much moisture is lost out of the egg dehydrating it. Chicks can be stuck inside the eggs while trying to hatch. This happens mostly if there is not a lot of humidity during the hatching phase (last 3 days). DO NOT OPEN THE INCUBATOR DURING HATCHING! I know everyone is curious about the new chicks, but do not open and check on them until day 21. If you open the incubator while hatching, the humidity drops rapidly and can shrink-wrap the chicks sticking them to the egg and leading to unsuccessful hatching. Chicks are fine in the incubator for 72 hours. They have enough nutrition from absorbing their yolk and do not need food or water during this time.

3) Turning/Rotating 

To mimic a mother hen, the eggs need to be rotated a minimum of 3x per day. This is where the type of incubator you get matters. An automatic egg turner is a lifesaver! If the eggs are not turned enough, the embryo can get stuck to the side of the egg, making it hard for the chick to hatch when it comes time. 

4) The egg selected for incubation

Clean, well-shaped eggs are best for incubation. Avoid eggs that are misshaped, too large, or too small compared to your average egg (different breeds of chickens lay different-sized eggs. Select the average for your breed). Fertility can be checked by cracking open your eggs and looking for a bullseye on the yolk to make sure your rooster is doing his job. 

5) Nutrition

The nutrition that the hen receives can play a huge role in the hatchability of the eggs. Hens that are fed a well-balanced diet will have healthier chicks. The yolk is what feeds the growing chick during development and needs to be high in nutrients. To set my chicks up for success, I feed all of my hens Henhouse Reserve®. It is a complete feed that offers all of the necessary nutrients for healthier eggs for both eating and hatching. Think of it as pre-natal care for your chicks. During the last 2 days of hatching, the chicks will absorb their yolk sac which is crucial for the chicks to become hardy, making the nutrition of the mother hen important to set the chicks up for a healthy start.

Hatching is a fun way to add to your flock, either hatching your own eggs or buying fertile eggs from a breeder. It does take some time to learn which methods work best for you. Making notes on what worked and what didn’t is very helpful for future hatches. Do research on chicken incubators! A great incubator can make a huge difference in hatch rates and overall monitoring. 

Happy Hatching!