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How Do We Know When a Chicken's Eggs Have a Chick Inside?

For those who have a small flock of chickens, it is often important to know if a given egg has been fertilized. If the eggs are for eating, the fertile ones are discarded while the infertile ones are refrigerated for later use. If your goal is raising chickens, the opposite is true. Either way, the difference between fertile and infertile eggs can be seen plainly if the egg is held up to a strong light, a process called "candling."

Things You'll Need

Bright lamp or flashlight
Cardboard "mask" for the light
2 buckets, baskets or other containers

Instructions

- 1
  Locate a bright lamp or flashlight, for checking the eggs. Cut a piece of cardboard to create a mask over the lamp, leaving a small hole for an egg to sit in. If you are using a flashlight, you can mask the light by wrapping your hand around it.
- 2
  Bring the eggs to your work space. Set up two buckets, baskets or other containers to receive the eggs as you sort them.
- 3
  Turn out the room lights. Turn on the lamp or flashlight. If you are using a lamp, place an egg on the hole in the mask. If you are using a flashlight, mask the light by wrapping your hand around the egg and the end of the flashlight, so the room stays dark but the egg is illuminated.
- 4
  Look at the illuminated egg. An unfertilized egg will glow uniformly, while a chicken embryo will be clearly visible in a fertilized egg. Clearly-defined blood vessels should also be visible in a fertilized egg.
- 5
  Place fertilized eggs in one container and unfertilized eggs in the other. If the eggs were intended for eating, refrigerate the unfertilized and discard the fertilized. If the eggs are for producing chicks, place the fertilized ones in an incubator and discard or eat the unfertilized.

Animals & Science