During their exploration of chicken embryology, youth learn that for a chicken to develop from an egg it must be fertilized. Most eggs sold commercially in the grocery store are from poultry farms and have not been fertilized. In fact, laying hens at most commercial farms have never even seen a rooster.
An unfertilized egg WILL NEVER develop a chick even if the mother hen incubates it. A fertilized egg COULD develop into a chick under the right circumstances. Even if you have a rooster, as long as you are collecting eggs every day you will not crack open an egg to find a developing chick.
Typically, supermarket eggs (of any variety) are unfertilized and thus can't hatch. Fertilized eggs, if exposed to the right conditions, can indeed hatch.
Eggs should be set as soon after you collect them as possible. Storing eggs for at least three days helps prepare them for incubation; however, fresh and stored eggs should not be set together. It is best to incubate eggs within 7 to 10 days of their being laid.
If the egg is fertile, then you should see a dark spot around the middle of the egg, with some spider-like veins beginning to form around it. If its not, you should just be able to see the shape of the yellow yolk inside the egg, without any signs of an embryo or veins.
If stored correctly, chicken eggs can be stored for up to 14 days before incubation. This is important as it means that you don't have to rush your eggs into the incubator, giving you time to build-up a clutch of eggs for maximum incubation success.
When you turn the eggs, you need to gently rotate them 180 degrees side to side, not end to end.
For those of you who do not share the hatching addiction: “candling” is the method used to determine whether incubated eggs are fertile or not. When candling, a bright light is held up to the egg to illuminate the shell's contents. Candling is best done in dark conditions, at night or even inside a dark closet.
Today, it is common practice to place eggs in the setter for the first 18 days, before transferring them to the hatcher for the last three days of incubation.
For a supermarket egg to hatch it must have been fertilised. And the vast majority of eggs on supermarkets' shelves, whether they are from ducks or chickens, will not be fertilised. This is because in commercial egg production male and female chicks are separated at about a day old.
After storage, they're put into an incubator at 99.5 to 100 degrees Farenheight (37.5 to 37.8 Celsius) to hatch them. The standard refrigerator temperature of around 5 degrees Celsius (about 41 degrees Fahrenheit) is well below the recommended temperatures, so would almost certainly sterilize fertilized eggs.
This is all fine and dandy if your chicken does have eggs to hatch, but sometimes, a chicken will sit on unfertilized eggs or even imaginary eggs. Hens raised without roosters can't lay fertile eggs, but they can still go broody and attempt to sit on a clutch of eggs. What is this?
Commercially produced eggs are laid by hens who are either in cages, barns or pastures - but without access to a male chicken. And without a male, a hen's eggs cannot be fertilised.
Many modern breeds and commercial hybrid hens will do nothing with their eggs other than lay them and walk away. Many have had the instinct to brood [sit on their eggs to hatch them] bred out of them over generations.
You'll see blood pumping through the heart of a tiny, developing embryo if you candle a fertile egg on Day 4. If the embryo dies at this point, you may still see a faint network of blood vessels inside the egg's contents. An embryo dying at this point will show a large, black eye.
Infertile. Yolkers: Yolkers are eggs that were not fertilized before being laid. They are clear, easily illuminated, and have a visible yolk in the center. They will not develop into a viable chick and should be discarded.
Signs of development will typically appear as a dark spot surrounded with numerous blood vessels. If this is what you see, then congratulations, your egg is viable and contains a chicken embryo. An unfertilized egg will not show any development at this stage and will simply appear clear when candled.
If not turned for long periods the yolk will eventually touch the inner shell membranes. When the embryo touches the shell membranes, it will stick to the shell and die. Regularly turning the egg will prevent this, and ensure healthy embryo development.
How Long Does It Take to Hatch a Chicken Egg Without an Incubator? Eggs hatched by the hen can take up to 25 days. The sweet spot for an egg to hatch is the same for the incubator, 20 to 21 days.
To incubate an egg naturally, you will need to have a hen which is prepared to sit on the eggs for a full three weeks. This is called a “broody” or “sitting” hen. The eggs in the nesting box is called a “clutch” or “setting”.
Any eggs stored for incubation should be kept at a temperature between 12 and 14 °C, at a high humidity of between 75 to 85 percent, and stored for no longer than seven days. Extra fertile eggs introduced under the hen from elsewhere should be introduced at dusk.
After ovulation the egg lives for 12 to 24 hours and must be fertilised in that time if a woman is to become pregnant.
Some embryos can survive at temperatures below 90°F for up to 18 hours, so do not give up. You should continue to incubate the eggs after the outage; then candle them 4 to 6 days later to see if there has been further development or signs of life.