Monday, March 6, 2017

Menopause in Birds



Do birds go through menopause? Now I have you curious, don't I. The answer is maybe. The conclusion is not certain since no fowl has come forward to speak out in defense of their moody ways. You may think I'm making this all up but surely you've seen the famous photo, 'Angry Bird'. Definitely true. I have one hen that stocked Robins, another who hates Magpies, and sometimes they just be in a fight with each other. PMS, menopause, who knows. Maybe it is just too personal for any of them to say something. Observation by scientist say they don't appear to have hot flashes and there is no diminished bone density.




What they do known is that some birds like the Macaw lay all their eggs by their mid 30's and yet live 2 more decades.  A type of menopause is suspected in these birds. Of course I don't have any Macaws flying around near my home in the wilds of Wyoming but it does not mean my brain did not wonder if I let my chooks grow old would they go through menopause? I only wondered for a few seconds, then I remembered that chickens do not run out of eggs before they die. They have all the eggs they will ever lay inside their ovaries before they even begin laying. Production does slow down after age 2 and substantially after age 4 but the chicken die long before exhausting the potential egg supply.  













This is the ovaries of a chicken. The eggs are in full view when you open up the hen's cavity. The first thing to develop is the yolk. There are tiny, tiny ones that are pink, and others at various stages of  yellow to orange. Notice the ample supply of blood vessels feeding these larger yolks.

Older hens sometimes have problems with egg production such as being egg bound because as the hen ages, so do the eggs. Egg production in chickens diminishes after age 2. Substantially after age 4 where they may only lay a few times a month.
This is the tube that runs from the ovaries and out. See the egg inside the uterus or shell gland. Here it is developing the hard shell as calcium forms around it. 
This is a better view.

This is what the egg looks like just before entering the shell gland.


If you want to know the details of egg production in a hen, this site is great.

As our ten year old says when we process chickens, "It is kind of grose but fascinating too!"





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