Things are now really starting to happen. We still won't be able to see anything if we candle at this early stage but inside the egg the embryo is beginning to take on a shape of its own, rather than being a simple cluster of cells.
If we opened it now we'd see some very obvious blood vessels on the surface of the yolk, and the embryo would appear as a tiny question mark in the middle of them.
This is the beginning of your chick.
The incubated egg at day 3
This is a critical day. The embryo has grown considerably since yesterday, the blood vessels have branched and the heart in particular is much bigger. Under a microscope the spinal column is clearly visible in the shape of a question mark.
Between 60 and 64 hours after the start of incubation the chick's nose, lungs, legs, wings and tail have begun to form.
The embryo has until now relied on the blood vessels developed during its first 48 hours for oxygen, but at about 66 hours into incubation it starts to need more air than those vessels can provide so the allantois forms outside the embryo and starts work. It has a dual purpose : it's responsible for collecting waste from the embryo and is critical in oxygenating it.
The amnion, a small sack filled with amniotic fluid also grows during day 3 and surrounds the embryo. Its job is to protect and cushion it from any jolts.
Please note: I have candled for the purpose of demonstration but I do not recommend candling this early in incubation. It's very unlikely that you'll see the developing embryo and there's a risk of damaging development by moving it at what is a critical stage.
An incubated egg candled at day 3. Nothing to see apart from an expanded yolk and possibly the air cell.
It's still rarely possible to see either the developing blood vessels or the embryo itself at this stage in the process, even with a very light-coloured egg. The yolk is becoming more pronounced and looks as though it's spreading but the main thing to be seen today in some but not every case is the air cell.
The air cell is found at the blunt end of the egg and is critical to hatching. It's the point at which the chick pips (pecks) through the internal membrane shortly before breaking through the shell itself.
The space between the membrane and the shell is the air cell and it needs to grow throughout the incubation process in order to provide the chick, as it's hatching, with enough air to breathe before it is able to make a hole in the shell and breathe the air outside.
As far as the eggs in the incubator are concerned - nothing. Just do what you've been doing for the past three days : make sure the temperature and humidity levels are kept stable and the eggs are turned at regular intervals.
However, in a couple of days' time we are going to begin to candle the eggs. If you've never done it before you may want to start practicing today, so that when we come to candle for real you'll have more confidence.
To see what exactly 'candling' means and how to do it, click on the picture to your left. That will take you to my detailed page explaining all about it.
I do recommend that you experiment by using a shop-bought egg, or one of your own eggs that you don't want to incubate.
At this stage, don't try to candle any of the eggs in your incubator. Firstly because it's far too early to see anything definite, and more importantly because accidents happen the first few times you try it (in fact accidents can happen even with those of us who have done it lots of times before!). Far better to practice using an egg which won't matter too much if it's dropped.
The first week of incubation is critical and the embryo is at quite a vulnerable stage as it begins to develop. Turning remains essential to prevent the embryo sticking to the shell, but any other movement is not something I would recommend.
It's very tempting to want to candle eggs at every stage - and if you have young children or grandchildren it will be hard to explain why they can't immediately see any development - but it's really better to leave it for at least another 24 hours - preferably longer.
One of my eggs seems to have a glunky liquid coming out of it. What would this be?
It's likely that an egg which seeps a glue-like substance has cracked. The main reason for this at such an early stage of incubation is that there was a hairline crack in the shell not picked up by candling before the egg was put into the incubator.
As the egg warms, the liquid inside it expands and seeps through the crack.
Can anything be done? Not once it's seeped, because seepage means the membrane has been breached and there's a danger that the contents of the egg will explode, releasing bacteria which might well contaminate and kill your other embryos. It needs to be removed straight away.
If it hasn't seeped but is cracked, some people recommend sealing the crack with candle wax, superglue or a very strong tape ('gorilla tape' for example); the danger is that bacteria may have entered the egg - it's risky but may be worth trying.
On each day of this series, I feature one of my own little chicks so you can keep your mind on the wonderful end result of everything we are doing.
This is one of my little Lemon Millefleur Sablepoot chicks. Sablepoots are a rare bantam breed, known for their lovely speckledy markings and amazing feathered legs. This chick is now a full-grown rooster (cockerel) who goes by the name of Clyde. The hen who I hatched at the same time is called Bonnie.
If you want e-mails personally delivered every day of incubation with a link to my pages telling you exactly what's going on during each step of the incubation process, you need to sign up for my series called "Hatching Happy Chickens".
If it sounds interesting to you and you'd like to know more, the image to the left is a link to details about exactly what you'll get.
And the best thing? - It's free (at the moment)!
The easiest way to follow my hatching series is to sign up for the e-mails. However, if you'd rather not do that, these are links you need to work logically through the series.
'The Incubated Egg' image is a commissioned artist's impression and, like all images on this site, is subject to copyright under the Copyright Law of the United States of America 1976.
Under no circumstances is permission granted to copy or otherwise use this image.
All other images of candling on this and other pages are my own and are not to be used without permission.
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