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.
After an embryo has died, the blood vessels start to break down. They then appear as streaks under the shell when viewed under the candling lamp. Candling will also reveal cracks in the eggshells. Eggs with cracked shells should be discarded.
The best kept secret in determining an egg's freshness is to see if it sinks in water. To try the egg water test, simply fill a glass or bowl with cold water and submerge the eggs. If the eggs sink to the bottom and lay flat on their side, they're still fresh.
If there are still unhatched eggs at day 21, don't despair. It is possible that timing or temperature went slightly awry, so give the eggs until Day 23. Candle any unhatched eggs to see if they are still alive before discarding them. Keep in mind that when hatching eggs, you will likely end up with roosters.
Dead embryos will typically look like a murky, dark shadow. Unfortunately, any eggs containing blood rings are not viable. Any clear eggs or eggs containing blood rings should be removed from the incubator at this point to avoid any rotting.
If you see a blood ring inside the egg with no embryo, or a tiny embryo with no visible eye, this indicates that the embryo stopped developing in the first three days.
If chick embryos develop to the pipping stage, or at first shell cracking at hatching, they are normally healthy enough to hatch unless some incubator adjustment prevents it from happening. The problem is usually caused by either 1) poor ventilation or 2) improper humidity.
The incubation period for chicken eggs is 20 to 21 days, and increases up to 30 days for other poultry. After sitting for some days, a broody hen can be given some newly hatched chicks and, if they are accepted, the original eggs can be removed and replaced with more chicks.
The longest incubation was recorded in the case of an egg of the mallee fowl (Leipoa ocellata), Australia, which took 90 days to hatch, compared with its normal 62 days.
Embryos have survived at temperatures below 90°F for up to 18 hours. You should continue to incubate the eggs after the outage; then candle them 4 to 6 days later to check for further development or signs of life. If, after 6 days, you do not see life or development in any of the eggs, then terminate incubation.
The shake test
While it may sound odd, shaking your eggs can also prove freshness. If you hear a sloshing sound upon shaking them, it shows that they are old and have potentially gone bad. As per the previous tip, if your egg's consistency is too runny it's probably stale.
After an embryo has died, the blood vessels start to break down. They then appear as streaks under the shell when viewed under the candling lamp. Candling will also reveal cracks in the eggshells. Eggs with cracked shells should be discarded.
Once the nest is “inactive”—that is, there are no viable eggs or live young—it is safe, and legal, to clean out a nest. We recommend disposing of those eggs, deceased young, and/or nest materials (e.g., if you're cleaning out a nest box) in a place where they won't attract insects to the nest area.
The presence of branch-like structures indicates you likely have a partially incubated egg. If you can't see any defined shapes, it appears solid, or all you can see is an air cell, discard that egg because it's likely gone bad. Likewise, if cracks in the shell are visible when candling, trash it.
It's likely that the chick will just hatch a little later. I have had chicks hatch as late as day 26, so don't despair. And do not be tempted to "help" the chick out of the egg.
Do all chicken eggs take the same time to hatch? No. Various things will influence hatch times: the age of the eggs, the health of the mother hen, fluctuations in the incubator temperature... Sometimes chicks hatch a little before 21 days, sometimes it can be several days after.
While I can expect to hear cheeping from within the eggs at any time now, it is most commonly heard around day 20. Chicks can hatch earlier or later than day 21 depending on whether temperatures were off a little bit one way or the other (too cool and they'll hatch later, too warm and they'll hatch earlier).
On day 20, the chick pierces the membrane into the air chamber. The chick breathes air for the first time, and you may hear the chick peeping inside the egg. This is called pipping.
Temperature too low and rela- tive humidity too high during incubation period. Check thermometer; 1ºF (0.6ºC) below 99.5ºF (37.5ºC) will cause late hatch. Old eggs. Set only fresh eggs; allow extra time for hatch by setting old eggs early.
If you use an egg from a young pullet that is too small in size, the chick may not have enough room to grow and develop properly. It may not hatch, or if it does hatch, the chick could be weak. So, when it comes to choosing eggs to use for hatching, you always want to use eggs that are regular in size.
Observe eggs for 14 to 21 days.
Most lovebird eggs hatch in 2 weeks while chickens take up to 21 days to hatch. If nothing happens to the egg past this period, the egg was most likely infertile or the embryo died and stopped its development.
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.
You will see that supermarket eggs are infertile. Did you know you can determine if an egg is fertile or not by looking at the germ spot? The germ spot is the white spot on the yolk. The non-fertile germ spot contains only the female's cells and looks like a solid white spot.
Non-Fertile egg, Notice the Germinal spot just above center on the Yolk. It appears as solid white spot. Fertile Egg. Notice the germinal spot looks larger and like a circle in this fertile egg.
When an egg is unfertilized, the germinal spot is small because it contains genetic material from only the hen. This is referred to as a blastodisc. With fertilized eggs, the germinal spot is larger and has a bullseye appearance with a clear, white edge.