Fertilization Question

[Kalin McClure]

Just a hypothetical question I was pondering:

We've all heard that a hen can lay fertilized eggs 2-3 weeks after her last breeding with a rooster.

I wonder, if a hen was separated from a rooster after breeding and then stopped laying for a short amount of time (let's say 5-7 days) from stress or some other reason, would the original 2-3 week span still hold true?  Or do you think the lack of production would extend it?  I'd assume the quality of sperm would degrade as time goes on, making fertilization less likely.  There's probably several variables that would affect it.  What do you think?

[John W Blehm]

My guess would be yes.  Sperm would be released after each egg laid to go fertilize the next egg being formed.  If she goes on hiatus that sperm already in the system may not still be around a week later to fertilize the next egg, but after that egg is laid I think more sperm would be released to at least fertilize the second egg after her break.  This is of course just my guess work, but if stored sperm stays viable for weeks when she is regularly laying then it should be viable for that same period if she isn't laying.  Also, consider that an Ameraucana that lays 4 or more eggs per week is considered a good layer, which leaves times a day and sometimes two between eggs and under normal circumstances all those eggs would be fertile.

When a pullet is hatched she already has all the tiny yolk sacs in her ovary that could potentially be the beginnings of all the eggs she will ever lay.  After she matures and as a yolk sac matures in her, it travels to her oviduct.  From here the yolk has a long journey before it is part of a complete egg.  By the time it gets to the uterus, where the shell is formed, the yolk and albumen or egg white are enclosed in a couple membranes.  It takes 25 or more hours for this complete process, from ovulation to an egg being laid.  Just before an egg is laid a protective film known as cuticle or bloom is applied to the exterior of the shell.  This covering helps protect the porous egg shell from allowing bacteria to enter.  If the hen was bred before ovulation the egg should be fertile and could be used as a hatching egg.  One mating can supply enough sperm for a hen to lay fertile eggs for weeks.  Sperm from a cock is stored in tubules in a hen.  Think of sperm stacked one on top the other in a small tube, with the last one deposited on top and the oldest sperm at the bottom.  As I understand it, when ovulation calls for sperm to create a fertile egg the last one in the tube, the sperm on top, is the next one used.