What’s in the Hen?

In Yesterday’s Post about butchering the Barred Rock Hen that kept escaping, I hinted at something interesting that I wanted to show you.  Perhaps you’ll find it interesting, too. I know I did.  We’ve butchered hundreds and hundreds of Cornish Cross meat birds over the years.  Those birds are butchered when they are between 8 – 12 weeks old, so their reproductive systems aren’t fully formed and visible.

In butchering the hen that was laying eggs, though, her reproductive system was, of course, fully formed.  I was able to see, up close and personal, a chicken anatomy lesson.  While interesting, it was also a little sad because you could see all of the eggs contained in the hen that will never be laid.  I’ll lay (pardon the pun) the blame for that squarely on her shoulders though.

Warning: GRAPHIC

So when I eviscerated the hen, here’s what came out:

I arranged it all on the cutting board where you can see the eggs in chronological order.  According to this informative site: http://articles.extension.org/pages/65372/avian-reproductive-systemfemale it gives a great explanation to what is going on within the hen.  I’ll give the Cliff’s notes from the article mentioned above.  I found it so educational. The yolks are developed in the ovary and then goes into the oviduct.  Within the oviduct, changes occur that add the albumen or egg white and then the shell, and this creates what we all know to be the incredible, edible egg.  It takes a little longer than a 24 hour day for the complete transformation from a yolk to an egg. 

Here is the full reproductive tract visual aid that I snipped from the aforementioned website:

Image Credit

If you follow the diagram above, you can follow the process of the creation of the egg.  First, the yolk enters the oviduct which is the long tube.

The infundibulum is where fertilization takes place.  An egg does NOT need to be fertilized in order to be laid.  It will just be non-fertile.  Many people falsely assume that you need a rooster for a hen to lay eggs.  This is not true.

The magnum is where the egg white (albumen) forms.

The isthmus is where the shell membranes form.

The Shell Gland is where the shell forms.  The shell is made of calcium carbonate.  This is why it is very important to give your hens a good supply of calcium.  We offer ground oyster shells free choice at all times.

The vagina provides the muscle to push the egg out.

And that is how the hen lays an egg.  Let’s take a closer look at the hen’s ovary from my dissection, shall we?:

So many eggs, you can't count them!

You can see many ‘future eggs’ (really the ovum) in various stages of development.  So you can look at this and get some idea of the number of eggs that were sacrificed by me butchering the hen.  If this was a goose laying golden eggs, I made a HUGE mistake!  A Barred Rock hen can lay up to 280 eggs per year.  I didn’t try to count all of the ovum, but it is a fair guess to say that there are hundreds of ovum in the photo.

Looking closer at two of the larger ovums (yolks) you can see that these were almost fully developed and the resulting eggs would have been fully formed and laid within the next few days.

I just thought it was a pretty neat biology lesson. 

We can see a thousand miracles around us every day. What is more supernatural than an egg yolk turning into a chicken?”
 S. Parkes Cadman