How soon the eggs will be fertile after you put a rooster and a hen together? If you separate them will the eggs a week later still fertile? Can you put a hen and a rooster together every other day and still get fertile eggs? Thanks

Shannon, The next egg MAY be fertile, if all goes well. You can move the rooster from hen to hen, in separate pens, every two or three days and eggs will be fertile. Some say that some eggs can still be fertile for up to 3 weeks after the rooster is removed. If I wanted hatching eggs, I would not chance it that long. CJR

When I butchered my laying hen, I found that she had 4 complete egg yolks inside. I do not think that a yolks can get fertilized, so I think you probably need to wait a week for a new egg cell to be dropped and fertilized with rooster sperm.

Aram, Each yolk and ova may be fertilized when it is released into the oviduct. So if the hen is laying (and no rooster with her), her first egg released after being with the rooster, will be fertile, except if one is being "finished" in the canal. The next one will likely be fertile. The roosters sperm may be present there for several weeks and so each ova that is released may be fertilized from the semen still in the canal. It is an interesting process, the putting together of the various layers in the eggs, the shell takes the longest to add, and it takes a little more than 24 hours for each egg to be "finished" and layed. There is a whole cluster of "yolks" at various stages of development in the ovary. What you see when a laying hen is butchered are some yolks that were maturing and would be ready to be released each day for several days, and many that were still being developed. A hen that is not laying will have the cluster, too, but the ova will all be very small. Production hens release an ova almost every day. Other pullets or hens will do the same, but usually for a shorter period of time, with taking time out to set, then resuming the "schedule". Janet Stromberg's little book "A Guide to Better Hatching" tells the process, with diagrams--a good thing to understand, when hens have problems with laying their eggs. CJR

I just read a interesting report. Some female birds lay fertile eggs without the presence of a male. The embryo begins to grow but never survives to hatch. There is a word for this kind of fertility which I cannot recall. I bet Rokimoto will know.

It is called parthenogenesis. There is a line of turkeys in Canada that have females that will produce male chicks without being fertilized by a tom. Only males are hatched because there is a mitotic duplication of the gamete's chromosomes. Normally an egg cell would have half the number of chromosomes as the parent, but something goes wrong and the chromosome number is doubled. You never get females because those gametes have a W chromosome (you get two W chromosomes upon duplication) and the poults need at least one Z sex-chromosome to be viable. They reproduce this line by taking the parthenogenetic sons and mating them to the females of the line. They then save the daughters for the next generation.

There is another type of parthenogenesis in reptiles and amphibians. Instead of two of every chromosome there are females with three of every chromosome. This is called triploidy. There are no males in these populations and the females reproduce triploid daughters. You can think of this as the ultimate inbreeding. There was a woman scientist that I knew that commented that we should do this in humans so that we could get rid of 1/2 the population that was just dead weight (the males). I think that they'd miss us, but you never know.