Agriculture Reference
In-Depth Information
One week.
At the one-week stage of development for all species, you can see
blood vessels and a developing body structure. The blood vessels form a network
but do not encompass the entire egg at this point. Duck and goose eggs can also be
candled at one week's growth and their shells make it easy to view growth. Turkey
eggs at one week are easy to identify once you get your skill level up.
Three days before the hatch.
If you remove all of the infertile eggs at the one-
week point, you're probably safe to refrain from candling again until three days be-
fore hatching. You can candle the eggs when you move them to their hatching in-
cubator or compartment. At this point you should be able to see a completely dark
structure inside the eggs of all poultry species. In a fertile live egg you can see a few
blood vessels that are distinct in shape around the edges. An egg about to blow looks
totally dark with no visible vessels, and will feel lighter than a living egg. In addition,
in some cases it will slosh inside. When an egg sloshes it is like a hand grenade, so
be careful: shake too much and you will have a mess.
Movement.
Chickens can usually be seen moving at day 18 of incubation. Ducks
are the most motile of all poultry species during the incubation process. When the
light is shined upon them through the air sac prior to their transfer into the hatcher,
they will kick and move around. Geese will also give a good kick at the light. As you
candle more and more eggs, you'll find that, as you approach the final days of incub-
ation, you can almost tell by the feel of the egg and its weight if it contains a healthy
embryo.
THE STAGES OF EMBRYO DEVELOPMENT
