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Candling Fresh Eggs
Week 1 of Incubation
Weeks 2 and 3
Week 4 of Incubation

Candling During Incubation: The First Week.
DAY 2 duckling development image
From Daily Changes in the Weight and Form of the Developing Chick Cornell Bulletin 205, by Dr. A. Romanoff (1931) duckling development image
What's Happening Now
Start of backbone; nervous system; head; blood islands: there is no heart yet, but a system of bloodvessels is forming that lies on the yolk (vitelline circulation). These will eventually line the inside of the shell, and support the embryo by getting oxygen through the shell and releasing carbon dioxide. eye; ears; heart forming
What to Look For
The germinal disc is now a bit smaller than the size of a dime, but it is still hard to pick out. The yolk has begun to change, and sometimes this is visible from the outside - the yolk will look darker, seems to be less 'round'. Note the changes in the yolk that are visible when the egg is opened (below - it looks almost stormy). There is a spoon in the last two pictures because the germinal disc was on the 'edge' of the yolk and I used the spoon to roll the yolk around so I could get a better image.
What to Watch Out For
It is still hard to be sure that an egg is fertile at this stage, so it is best to wait a few more days before deciding whether or not to discard one. There is no danger of an egg going 'rotten' at this stage (unless it was already rotten when it went in the incubator).
[1] Watch a short clip of a 30-hours old egg being candled. [2] Watch a short clip of a 30-hours old egg being candled.
[3] Watch a short clip of a two-day old egg being candled. Can't watch the movie? Download the Quicktime media player.

farm/candling/day_2.txt · Last modified: 2021-04-09 10:49 by becker