Feeding crushed eggshells vs oyster shells

What do you feed to your flock?


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Calcium carbonate (CaCo3) is 40% calcium.
Oyster shell is 95% calcium carbonate.
Good quality egg shell is 94% calcium carbonate. Some studies published report as low as 78% calcium carbonate - the remainder is mostly phosphorus and magnesium and trace amounts of zinc, manganese, sodium and other minerals.

So in the end, there is very little difference.

The major difference is in particle size. Oyster shell's larger particle size stays in the upper digestive tract longer and thereby comes in contact with the calcium absorption sites in the small intestine at night when the egg is in the shell gland.
Over 12% of consumed calcium isn't absorbed. Especially a good percentage of small particle CaCo3 isn't fully digested or absorbed because it doesn't stay in the digestive tract long enough. That is what makes oyster shell such a good source of calcium.
Also, if phosphorus and D3 are inadequate, that further affects how calcium is utilized.
 
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Mine go through oyster shell faster. I gather egg shells, let them dry on a cookie sheet and bake at lowest oven setting (150 F) and then crush and put out in small quantities daily. I think mine produce better shells over time on oyster shell. Their egg shells are always decent and much better than what's at the store, and depends on the hen too, but with oyster shell their egg shells become nearly bullet proof!
 
For those of you feeding eggshells, aren't you afraid of the correlation to them starting to eat their own eggs?

Nope! As I said, I wash them and microwave them before I crush them. Not much to look or taste like an egg. I also remove each morning's eggs pretty promptly. I also scramble and cook any egg I give them to eat. In 3 years my hens have never broken or tasted a raw egg. So I'm not really concerned.

On a different note, I find my rooster in the egg shells too. I feed all flock so he isn't getting calcium that may not be best for him but he goes right for the eggshells. Gotta trust he knows what he's doing...
 
For those of you feeding eggshells, aren't you afraid of the correlation to them starting to eat their own eggs?
Mine do not seem to bother with the eggs and due to work schedule sometimes my eggs don't get collected until 2nd day. I just pop in microwave 30 seconds and crumble. Like Iamrainey, I also feed All Flock and my rooster is interest in the egg shells, doesn't really bother much with the OS.
 

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