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How do chickens start laying eggs? Well, when a mommy chicken and a daddy chicken love each other very much…… OK, stupid joke aside, you probably want to know the actual physical process by which a chicken’s egg is produced and laid. And I’m betting you just want to know the basic process that occurs and not some sort insanely in-depth description of all the chemicals and such involved…..you know, the kind of thing only a biochemist would care about. I will however include all proper names for the organs involved as best I can.
Let There Be Light! No, seriously, the whole process begins when the chicken opens its eyes in the morning. As soon as the chicken sees light it triggers a gland in the brain to release an egg cell (called an oocyte) from the chicken’s ovaries. If fertilized, this oocyte would eventually develop into a chick. The release of the oocyte, fertilized or not, begins the overall process of egg production.
The oocyte travels into the uterus where it gradually grows the nutrient rich yolk. While the yolk is getting larger, the uterus fills in with albumin, the stuff we usually call egg white.
Once the yolk and albumin are finished forming, the uterus will begin to form a breathable skin called a membrane around the whole thing. This membrane will hold the yolk and white together and allow air to get to the growing chick (if fertilized). From here the membrane begins to form the shell from minerals (mostly calcium) in the chickens body.
From here the egg travels down a vaginal canal in preparation for being laid. The egg will be laid from an external opening on the chicken called the vent. The vent of the chicken also connects to the chicken’s digestive tract, and is used for both feces and eggs. Obviously a chicken’s egg isn’t covered in feces when laid, so what’s going on?
The egg is held inside the end part of the chicken’s vaginal canal, called the cloaca. The cloaca at this point will block off the intestinal tract of the chicken before turning itself inside-out to lay the egg. This ensures that the egg is sterile when it is laid so that mold or bacteria won’t start growing on the egg.
How Do Chickens Start Laying Eggs
This whole process, from beginning to end, takes around 25 hours. Chickens will typically lay only a single egg a day until the have around twelve; at which point the will start to incubate the eggs. In the case of fertilized eggs, the developing chicks in the previous eggs will stop growing until the incubation process starts. This ensures that all the eggs will hatch at the same time.