Artificial incubation

[Guest The Big Fish]

I trawled through my old website database and managed to pull an old post about incubation.

 

Artificial incubation to me, is not only interesting but is an art in itself (if you wish to get good results) I have done a couple of drawings to get started on the subject that show you the basics of egg structure and how the egg works. If you have a look at the first one it will show you that an egg is more complicated than you might think. It’s made up from several components. You have the shell, two membranes, thin white, thick white, the device which holds the yolk in place (chalazae), yolk and the germinal disk (trust me you will never view the little old egg in the same way after reading this, lol).

 

 

First I suppose I should talk about incubators. Two types, still air and forced air. Still air incubator: is a device that holds the eggs at a certain temperature, the heat is usually (nowadays) generated by an electric heating wire, very similar to how and electric bed blanket works. The heat is produced by the wire and then the heat radiates downwards onto the highest point of the egg. The eggs are lead on their sides just as you would put one on a worktop. When using these types the temperature at the highest point of the egg is 39 degrees centigrade, this produces a temperature of 37.5 degrees (blood temp) in the centre of the egg.

Most incubators nowadays have automatic egg turning capabilities.

Forced air incubators: use a fan to keep the air circulating all around the inside of the machine at a constant temperature: 37.5 degrees centigrade, the whole of the egg remains at this temperature unlike the still air types. Again most of these machines have auto egg turning. The eggs in these machines are normally stored in special plastic egg trays and are kept point down. The trays tilt from side to side to provide movement for the egg.

The reason for egg turning is to prevent the contents of the egg from sticking to the shell and membranes, if this were to happen, there would not be sufficient air and carbon dioxide transferral from the developing chick through the eggshell.

 

The chalazae is made from an elastic type material that is twisted the opposite way on each side of the yolk, this prevents the yolk and embryo from twisting all the same way when turning occurs. The yolk will always twist back to its original position. I will deal with pheasant eggs for the time being. The egg takes 21 days of incubation and a further three days of the hatching period. During the hatching period the turning of the egg is stopped. During incubation the humidity should be at about 30%, but due to climatic changes, very rarely is this achieved, normally its much higher, yet hatcheries still continue to add water into the incubator to boost the humidity. In my opinion it’s really not needed. At 21 days of incubation, the eggs are transferred to a still air hatcher where turning stops and the humidity is increased to about 40% by adding a little warm water underneath the eggs. Some people believe that its the amount of water added that is crucial, when really its the surface area that counts, a wider-longer water tray = more humidity. During the incubation period the normal practise is to candle the eggs, this means shining a light onto the top of the egg (the top is the other end from the pointed end) to show the development of the growing embryo. After 7 days of incubation, if the embryo is growing it will be apparent, you can see veins starting to grow and the the egg will start to appear dark. If the embryo did not fertilise, the egg will appear clear and should be discarded (not eaten). Candling normally takes place again at transferral into the hatcher.

 

Once in the hatcher the chick will break through into the air sack where it will take its first breaths, at this stage the chick has a tiny raised part on the top and end of its beak, this is called the egg tooth and is used for breaking out of the egg. Day 23 and the chick will break through the shell, just a tiny portion of the shell will be broken and this is called pipping. After this, the chick remains like this to rest, usually for a few hours, incidentally this is when most predation in the wild will take place, the predator, whether it be fox, stoat etc can hear the sounds made by the chick still inside the egg. Once the chick is ready for the final stage, it happens really quickly, they start off at the pipping hole and go round the top of the egg in one chipping motion. Then they are out of their shells.

Once hatched, they are still wet and weak and need time to regain energy. The yolk sack has been absorbed into their abdomen and will power them for about 24 hours. Also I should mention that during incubation a large proportion of the shell calcium is transferred to the chick for the development of bones. This also helps the chick to hatch because the shell is much thinner. On day 24 once the chicks are mostly dry, they are put into chick boxes that have shredded paper or wood wool in them to dry off completely before they go out to the rearing sheds.

[IanB 0]

Good article BF, interesting reading, now were did I put the frying pan...

[Guest traceyg]

Thanks tbf very useful great help