After incubating for approximately 42 days, an ostrich egg is usually ready to hatch. Every ten days during the incubation period we pulled each egg out of the incubator for candling and weighing.
Candling is used to look inside the developing egg. Using a special light box, we candled the eggs on days 10, 20, 30, and 40; the developing embryo can be seen to grow through the candling process as it develops. It's important to check the air space at the top of the egg is checked; typically it increases in size as the moisture leaves the egg through the pores. Every ten days a pencil line is drawn it to record the changes.
Remember that fading chick problem? As I continued to search high and low for an infection, I realized inadequate moisture loss during incubation was the likely cause of the weakness we saw in the fading chicks.
If I add a vet pack to the cart and change the logo to Oak Country Veterinary Services I'd have myself a cool veterinary vehicle
Each egg needs to lose a specific amount of weight for it to lead to a healthy baby during hatch-out. This weight loss is a direct correlation of moisture loss in the egg. If an egg did not lose enough moisture, the chick hatched out soggy, too weak to thrive.
That's why we weigh the eggs every ten days, to chart this moisture loss. If the loss is too much or too little, the egg can be manipulated accordingly, usually by putting it into another incubator at a higher or lower humidity level. The idea is to put the egg in an environment where water vapor is leaving the egg through the pores at the perfect rate; if the egg is too wet, we set it inside a drier incubator and vice versa.
Around 42 days the eggs are moved from the incubator into the hatcher. The hatcher is different than the incubator; it doesn't turn back and forth every half hour. Periodic rotation is needed during development to keep the internal membranes from sticking together and gumming up the development process.
Eggs are placed in the hatcher to hatch, hence the name.
The first step in the hatching sequence is the internal pip. Pipping is the process whereby the baby breaks its way out of the egg, and the first move occurs when the head breaks through the inner membrane, that thick rubbery white lining that separates the growing baby from the air space. Internal pip happens when the baby pushes its head through the inner membrane into the air space and starts to breathe air through its mouth into its lungs. A healthy chick first shows internal pip before any crack in the shell occurs, and a light box allows us to visualize this as the baby moves its head into the air space.
Now the chick rests for a while, allowing lung respirations to strengthen while the process of breathing through the egg shell shuts down. The blood vessels running from the belly button along the inside of the eggshell constrict, pulling all the blood into the chick. Finally just before hatching the chick pulls its yolk sac inside. Now with the yolk sac internalized, and the blood vessels running out the umbilicus shut down the baby can come into the world.
When egg respiration shuts down the chick begins external pip. Using the pointed protuberance on its beak, the bird can quickly tap a crack in the shell, making a hole in the shell above the air space. Once the head can see outside the chick rests some more then uses its legs to explode from the shell.
So, for now, we kept both the incubator and the hatcher in our little house, successfully hatching out many in spite of the fade problem. But with chicks hatching out, we needed to find room for them. We cleared the guest bedroom of all human furniture and put chicks to bed in the room inside four by four-foot nurseries Mary used for raising dogs.
Audiobook coming soon