Posts : 3535 Novaliches, Quezon City Join date : 2009-02-21
Subject: Candling eggs to check if fertile Sat Mar 14, 2009 4:20 pm
CHECKING EGGS TO SEE IF THEY ARE FERTILE
Candling Eggs: Eggs can be candled when they are 4 or 5 days old. All you need is to buy a small penlight flashlight like a Mag light or any small bright flashlight. Hold the egg in front of you (about 1 foot or so away at your eye height) and hold the flashlight very close behind the egg so you are looking through the egg with the flashlight pointing towards you and you should be able to see red veins on the inside of the shell and a small dark spot which will be the embryo. If the egg is clear through it is probably not fertile. You can also tell by the egg color as fertile eggs well be bright white while infertile will be a dull white. If you do not see the lines (veins) or dark spot inside after 10 days you can probably throw them out. Before you open any nest box to remove or check the eggs you should always tap on the box door lightly so the hen expects you and you do not frighten her and possibly have her trample the eggs. In time the hen will know it is you and get out of the nest box for you. You can then take an egg and candle it to see if it is fertile. Do not do this too often and never shake the eggs. Sometimes the hen will wait a few days before sitting on them so the 10th day is the safest time to say whether they are OK or not. Note: This process may only work with white eggs. Colored eggs may be difficult to see through.
Bobbing for good or bad eggs when Candling does not work: This procedure can be done after they are past their due time to hatch and you cannot determine if a chick is inside by candling them. Try and place the egg in a cup or small bowl of room temperature water as easy as possible to minimize its movement. Use a spoon to slowly place it in the water if you feel uneasy with placing it in slowly by hand. If the egg continues to move or bob, there is probably a chick inside. If the egg stops and stays still it is probably infertile or dead in the shell. You should allow each egg to sit for 10 to 20 seconds before you determine if they are good or not. You can then place the good eggs back in the nest and remove the bad ones. This process is mostly used on dark or colored eggs such as Quail, or eggs past their hatch date.
NOTE: Bobbing the eggs in water will not harm them, as the egg shell is porous for air circulation, but has no holes to allow water to soak inside unless the egg is already cracked somewhere. The egg would have to sit in water longer than 15 minutes to cause any harm. Any eggs that show cracks should not be bobbed in water. The egg shell is porous so oxygen can fill the gap between the membrane and the shell so when the baby breaks the membrane and tries to get out, it has oxygen to breath until it breaks the shell with its beak.
For safety you can usually discard eggs that are 7 to 10 days past their normal hatching period if you have marked the eggs when they were hatched or when the hen started laying on them which would be better.