Egg Fertility

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Egg Fertility

Post by Katy on Sat Oct 01, 2011 9:00 am

If you break open a fertile egg and examine the yolk you can see a spot (sometimes whitish in colour) on the surface. The spot is about 3-4mm in diameter. It is formed by the union of a single cell produced in the ovary of the female with a single sperm produced by the male. When these two cells fuse, the resultant cell divides into two and these two cells grow and divide again and again, until by the time the egg is laid, the mass of cells is visible as the germinal disc.

This is the yolk from a fertile speckled sussex egg.

An infertile egg will also have a white spot, but a fertile egg will have a spot that shows some development and multiplying of the cells. Sometimes the spot on the fertile egg will be a bit bigger due to the growth. In the picture above you can see the circle of cells in the centre which have been growing. Some people describe it as a 'doughnut'.

By the time an egg is laid the cells have begun to multiply and you can see the blastoderm if you look carefully. When you crack an egg onto a saucer you can see it. Sometimes it's necessary to carefully roll the yolk over if it's on the down side.
A fertile Egg

And now an infertile Egg

And another couple of infertile eggs:

Within the egg, the yolk is anchored in position by chalazae on the top and bottom. These look like a white, sometimes curly membrane and are not related in any way to fertility. They keep the yolk in position.

The other things that are sometimes seen in the egg is a meat spot or a blood spot. These are also unrelated to fertility. Blood spots can occur if there is a tiny bleed in the ovary at the time of the development or release of the yolk. For more information about meat and blood spots go here.

The fact that an egg is fertile does not necessarily mean that it is of good enough quality to hatch successfully, or even produce a healthy chick. Many factors come into play for that outcome. There is more information on hatchability in a post on here.

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Join date : 2011-09-30
Location : Morayfield QLD

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