Q: Does a fertilized double yolked egg hatch twin chicks?

By: Blend Bardhi, Rodrigo Fuentes, Jason Welsh and Rob Kyle

UnfertilizedFertilized

RoosterHen

???Two Chicks???

How does the hen make an egg ?“Catcher’s Mitt”

1. Follicles drop down from ovary into the infundibulum (catcher’s mitt).

2. The yolk travels through the oviduct where the albumen (egg white) is formed.

3. The incomplete egg passes through the shell gland where deposits of calcium are made to form the shell.

4. The finished egg eventually leaves the body through the chicken’s cloaca.

Hen Oviduct

Why are there double yolked eggs?

1. Two yolks are released from the ovary at the same time.

2. The two yolks then both go through the cycle of a normal one yolked egg.

3. When the complete egg is released from the cloaca the two yolks are surrounded by the egg white and the egg shell just like a normal egg.

Two chicks developing inside one egg

A fertilized yolk and an unfertilized yolk in one egg. The Yolks surrounded by blood are the fertilized follicles.

Developing baby chick

The fertilization of the chicken egg.1. Rooster sperm has an extremely long life

span.

2. This sperm can be stored in the hen’s infundibulum for up to 30 days.

3. When the ovary releases a yolk these sperm can fertilize the egg.

4. A fertilized egg will then hatch after it is laid.

5. A TABLE EGG IS AN EGG THAT IS NOT FERTILIZED.

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Will a double yolked egg produce Two Chicks?

1. Double yolked eggs rarely result in two baby chicks.

2. When fertilized both embryos potentially could develop normally, due to a lack an extra air cell one embryo out competes the other. The surviving embryo then hatches one chick.

Fertilized

Unfertilized

Will a double yolked egg produce Two Chicks?

Often times both chicks will begin to grow and will ultimately compete with each other so much so that neither chick survives and the egg never hatches.

Fertilized

Unfertilized

What have we learned?What have we learned?

1.1. The yolk serves as a food source for the The yolk serves as a food source for the developing chick.developing chick.

2.2. Double yolked eggs occur when two yolks Double yolked eggs occur when two yolks are released from the ovary simultaneously.are released from the ovary simultaneously.

3.3. An egg is fertilized in the hen’s An egg is fertilized in the hen’s infundibulum after the yolk is released from infundibulum after the yolk is released from the ovary.the ovary.

4.4. In a fertilized double yolked egg, one of the In a fertilized double yolked egg, one of the developing embryos out competes the developing embryos out competes the other for space and resources.other for space and resources.

5.5. Or, neither chick survives. Or, neither chick survives.