Mkulima today incubation is often viewed as a mysterious process, at least in part because the growth process is occurring behind closed doors inside the chicken eggshell. In order to keep you on the right path to riches, today we cover a guide on candling eggs for quality.

This is how to check egg quality by candling in egg production. The quality of the chick is only as good as the egg from which it is hatched, which depends upon the breeding pair’s diet.

The ability to see, in part, the development of the chick in the chicken egg helps us understand the growth process and helps improve our incubation results. The process of viewing the internal contents of the chicken eggshell is called candling.

This name came from the use of candles as a light source in the early days of incubation. Candling eggs for quality involves using a light beam in the form of a candling torch.

Read more

Pre-incubation checklist in poultry farming

Why you will pay more to feed your animals in 2021 as manufacturers close shop

9. factors to consider when buying an egg incubator

In a dark room, hold up the blunt end of a chicken egg up to a strong LED candling torch allowing the light to penetrate the shell and illuminate the inside of the chicken egg.

When should you do candling eggs for quality?
Make notes about your incubation and candling observations so that you will be able to remember what to do next time.

The main thing to remember about candling eggs for quality is that it is used to build an experience factor. Don’t expect to understand all there is to know the first time.

After you have done it a few times, you will be able to cross-compare what you are seeing and have the ability to make adjustments because of it.

How to check egg quality through candling

After a little while, you will see the chicken eggs that are different and be able to tell a good one from a dud.

The first time is prior to setting the chicken eggs. This enables the observation of the freshness of the chicken eggs, which relates to storage conditions.

Remove eggs with faults. The second time is 1/3 way through incubation. This will indicate the infertile or clear chicken eggs and will give the first humidity indication.

The third candling is after 2/3 through incubation. This will give a good idea of the continued development, and the critical moisture indicator. This is the last chance for humidity adjustment. The fourth time is at the transfer to hatcher (3 days before hatching for chicken eggs).

For other species, candle about three days before the due hatch date. This candle will indicate that the humidity has been correct and that all is well.

When candling, compare the air cell size to the image above. If the air cell is not tracking well, such as the air cell is too small then reduce humidity in the incubator.

What can you see by candling?

  • State of the freshness of the chicken egg
  • The size of the air cell at setting is very important. If the chicken egg has dried more than its quota of moisture loss pre-hatch, then the chicks will be struggling to hatch at all.

Many diseases including infectious bronchitis can cause discoloration and some damage to the shell.

When illuminated during candling, shell faults become apparent. Chicken eggs with these faults should not be set in the incubator, as they are known to have poor hatchability.

Shell faults include mottling, hairline cracks, and chalkiness when you do candling eggs for quality.

Development of the embryo

How to check egg quality through candling. With the high-powered lens-focused candlers, the development of the embryo can be seen from 24 hours onwards.

1/3 way through incubation the spidery blood vessels are very obvious.

Early incubation failures and infertile eggs

Chicken eggs which are clear at one week are either infertile or have suffered early embryo mortality. Blood rings indicate early embryo death, possibly due to low vitamin K and or jarring.

1/3 way through incubation: blood ring will be seen.

By the end of the second week, the chicken egg will be a solid mass, with only the air cell open. The point of the small end may still be a little cloudy, as there should still be a little unabsorbed albumen at this stage.

The movement of the embryo is easily seen at this stage, though lack of movement should not be taken as a sign that the embryo is dead.

By watching the development of the air cell and monitoring the weight we have an extremely accurate method of relating air cell growth, humidity readings in the incubator, and weight loss.

Three days before the hatch, the chick is fully formed. If you candle on the 19th and 20th days, the beak of the chick will be seen in the air cell *Chicken eggs only.

Moisture control in the incubator (humidity)

During the incubation process, the chicken egg will lose an average of 13% of its weight as moisture loss. The limits of this loss are a minimum of 11%, and a maximum of 15% (chickens, ducks, and geese.)

Insufficient weight loss will mean wet and sticky chicks, with a possibly delayed hatch. Too much weight loss will result in small, noisy chicks, with increased post-hatch mortality.

Moisture loss of 13% will mean that around 30% of the chicken egg volume will be air cell. Weighing is not essential but certainly helpful with difficult species.

Other factors which may affect the quality of your chicken egg including:

  • genetics
  • handling
  • porosity of shell
  • age of the parent
  • storage.

For more information on getting, the best incubators for commercial hatching call us on 0726572541.

Having an agribusiness question? Do you know of a successful agribusiness venture or story that you wish to share? I would like to hear from you. Send me the TIP(s) at

Like and follow MkulimaTODAY on Facebook | twitter | Pinterest | Instagram | Group share this article and leave comments or questions or WhatsApp me +254700761190 on what you would like me to answer in the next article.