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.
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.
Some of the chicks that hatch can be deformed or non-viable. Some eggs will contain embryos that have died during the incubation period. It's good practice to break open unhatched eggs. It can often show you if the egg was fertile, at what stage the embryo died, and possibly why.
How long can bird eggs be left unattended? Most bird eggs will remain healthy for up to two weeks before incubation starts.
Here are the most common reasons that few, or no, chicks hatch: Eggs were infertile, old, or improperly handled before hatch. Temperatures were too low, too high, or unstable during the hatch. Humidity levels were too high or too low.
“First, for the Day 22 and no hatching chicks situation, it certainly does no harm to leave the eggs alone for another day,” he says. “They possibly could hatch, although it's fairly unusual for eggs to hatch and produce healthy chicks after Day 23.
Always set eggs under a broody hen within a week of her becoming broody. Few hens will stay on the nest forever and most will leave the nest after 3.5-4 weeks when the eggs haven't hatched.
Below about 27°C (80°F) no embryonic development takes place. Prior to incubation, eggs must be stored in this temperature range, ideally around 15°C/59°F. Below this threshold ice crystals will start to form in the egg and permanently damage may be done to internal structures meaning the egg cannot hatch.
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 no fertile eggs available or the broody sits on an empty nest, broodiness can continue long beyond three weeks, resulting in negative health consequences for her and problems for other hens. A broody eats, drinks and eliminates waste once or twice a day at most.
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 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.
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.
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.
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.
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.
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.
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.
The female bird lays eggs in the nest. She then sits on top of these eggs to provide warmth until they hatch. This is known as brooding.
Successful hatching is greatly reduced. The zone of suspended development: 28.4 to 80.6°F or -2°C to 27°C. Eggs at this temperature don't develop at all. Freshly laid eggs can spend a lot of time at this temperature with no harm to the egg or embryo.
Care of a Broody Hen
Just let her sit on the eggs in the nest box, but know that it's best to move her and the clutch of eggs to a larger nest box that measures at least one-foot square. A nest box of this size will allow the hen to turn around, move a bit, and set up for the chicks.
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.
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).
And candling does not harm your eggs. Just as the mother would naturally leave the nest for a short time each day, you can safely take your incubating eggs out of the incubator for the few times you will be candling them.