How an Egg is Formed

Egg Formation Process
[reposted from my blog at Capper Farmer:

Laying an egg is triggered by receiving adequate sunlight through a receptor in your bird’s eye which triggers hormone production mainly in the pituitary gland. The average amount of light required to begin egg production is about 14 hours. This is why your hens produce more eggs during the spring and summer months than in the fall and winter months. Your chicken and turkey hens will produce very well from March until September, seven months of the year. Your ducks hens and goose hen will produce from February until June and September through October, seven months of the year.   The number of eggs a hen lays in her lifetime is determined by four major factors: species, breed, nutrition and shelter.

  1. Needed amount of light (14 hrs) triggers the production of hormones. Ducks, turkeys and geese do need a male present to produce eggs well; chickens on the other hand do not.
  2. Hormones ripen an ova (white dot on yolk) and development of a yolk occurs about 9 days later
  3. The yolk and ova are released into the oviduct
  4. As the yolk and ova enters the oviduct, sperm join with the ova and fertilization occurs. Life begins even as the rest of the egg is being formed.
  5. Sperm longevity is limited to 4-5 days. There is no way to tell if an egg is fertile until you crack it open or if you candle the egg and look at development of the chick at least 4 days into incubation.
  6. The egg white is formed around the yolk and ova.
  7. The shell membranes formed around the egg white, yolk and ova.
  8. The shell, which is white is formed here.
  9. The pigment of the shell, which is determined by breed, is added. Then the bloom is added, covering and protecting the shell.
  10. The egg is then “birthed” through the vent.
  11. This process takes about 24 ½ hours. Therefore, the most you can have is 1 egg per day.
  12. In order for this egg to be hatched, the right conditions need to be met. Of course the egg must be fertilized, than the hen or artificial incubator, must sit on the eggs maintaining a temperature of 99 – 102 degrees and humidity should remain at 65%. The eggs must be turned twice per day. After 20-35 days 95% of the fertilized eggs should hatch if the right conditions have been met.

18 thoughts on “How an Egg is Formed

  1. gourmetmomchef

    Thanks for the very interesting info, I never knew the process, just enjoyed the eggs. I am thankful every time I see an egg in the nest, I know it is alot of work for the hens. I have had chickens for 23 years, and have raised my own a few times. It is very worth the effort and they are irreplaceable for their flavor

    Liked by 1 person

  2. Safar Fiertze

    This is very interesting and useful information. I hadn’t realised that light was a trigger for egg production hormone release. Although I should have: there is research to suggest the role of light in human menstrual cycles. I think also that the pineal glands of avians in general have receptors that directly pick up sunlight as well as via the eye. Thanks for sharing this – will help with chicken diagnostics in the future.

    Liked by 1 person

    1. Really, it is ovulation. Menstruation occurs in mammals. Just wanted to correct a previous comment which wasn’t appreciative of the subject. 😉 Under natural conditions, birds ovulate frequently (Spring season in particular). Birds are more fragile, and have a higher mortality rate and require robust reproduction-multiple babies to increase their chance of survival. Therefore they lay multiple eggs over many days until they have a clutch appropriate for their species/breed etc. Of that clutch of eggs, only about 55% of the eggs hatch on average. They have to play the odds, just like the rest of nature, and God has given them the ability to flourish.


  3. KIA

    knowing that the egg is the monthly menstration of another animal (naturally monthly, but we have engineered them to lay more often for our consumption), why would i ever “eat” another egg?
    how is it that we feel privileged to treat other animals this way just for our convenience?


  4. Pingback: How an Egg is Formed | How to Provide

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