I have read a lot about how to prepare egg shells for chickens, and I wanted to share what has worked for my chooks – and also why and when you need to provide a source of calcium for laying hens in the first place.
Why Chickens Need Calcium:
Chickens require a lot of calcium, to build and support healthy bones – just like humans! – but also to produce eggs.
Don’t Feed Young Pullets Calcium:
Although hens need calcium, giving chickens additional calcium shouldn’t be done at a young age. Young chickens, who are not yet laying, don’t needed extra calcium. They aren’t producing shells and the calcium they need for bone development should be found in their feed, as long as they are fed a high quality feed designed for their age. When they’re chicks, I do supplement their water on the advice of the hatchery I purchased from. But while some minerals and vitamins are just peed out if too much is consumed, too much calcium at this age can damage a chicken’s kidneys and lead to health problems and even cause death. So no added calcium for chickens who aren’t laying!
Feed Chickens a High Quality Feed:
Make sure that once your chickens are laying you buy a high quality layer feed as it should, ideally, contain everything they need, including calcium. I have found there is a lot of difference in the quality of feed – one feed I got actually created nutrient deficiencies in my second batch of chicks and caused developmental leg problems. Once I added the vitamins that were missing, the leg problems went away in one of the affected chicks, but for another it was too late. I had bought from a feed store closer to me, thinking they’re all the same. Now I drive to another town to get better quality, organic layer feed and it seems to make a huge difference.
Not All Hens Need the Added Calcium:
If your hens are laying perfect eggs, they may not need extra calcium. Commercial layer feed should have everything a chicken needs and it’s typically designed with the perfect nutritional balance. But if your chickens get lots of food scraps and extra nummies, it can throw off this balance and create the need for more calcium, even if they’re eating a high quality feed. And if you start to see shell problems, like thin shells or weak spots, your hens might need some extra calcium to help their bodies make good, strong egg shells. Keep in mind, however, that shell problems can also be caused by stress, over crowding, certain diseases, changing from chick feed too late, etc. So adding extra calcium may not solve all shell problems, but if your chickens aren’t eating only layer feed, it’s a good place to start.
Don’t Mix Calcium in With Food:
Theoretically, chickens can determine if they need calcium so offer it alongside feed, not mixed in, so chickens can eat it if they need it. You also don’t want roosters getting too much calcium, another reason not to mix it in with their feed. Offer it separately, in another container or sprinkled on the ground.
Sources of Calcium for Chickens:
There are two popular sources of calcium for chickens: oyster shells and feeding their own shells back to them. I give my chooks both because I have read that they really benefit from oyster shells as a calcium source because they are more slowly digested – but egg shells are free and the chickens don’t gorge on them. So I give them both!
Pros and Cons of Oyster Shells:
Oyster shells are an easy source of oyster shells. They can be bought by the bag at the feed store and chickens love them. That’s the only down side: I found my chickens really loved them, and I suspect some of them were eating more than they needed because some eggs developed little bumps and rough ends on them – those are calcium deposits and a signs of too much calcium.
So I couldn’t trust them to pace themselves when it came to oyster shells. As a result, I only give them from time to time.
Pros and Cons of Feeding Chickens Their Egg Shells:
To supplement their calcium intake in a less tasty way, I started offering the chickens oyster shells a little less frequently, and then their own egg shells from time to time. Never feed chickens eggs shells from another source (like grocery store eggs or egg shells from a neighbor) as it could spread disease. I have read that there is a risk of salmonella from feeding egg shells back to chickens (even their own egg shells). But this was sourced from a company selling calcium supplements, so they may be biased. There is also a risk of chickens putting two and two together and starting to peck at or otherwise sample their own eggs. For a long time, I was giving my hens oyster shells for calcium and they still occasionally pecked or sampled an egg. When I switched to giving them back some egg shells, the instances of egg pecking neither increased nor decreased.
On the plus side, they don’t seem to like the egg shells that much – when I first brought out a plate they thought it was a snack, and they were super excited. When I set it down, they stared at it, little wings slumped in disappointment. Then they looked up and glared at me. Looked down at the shells again. Glared at me. They were not happy.
I backed out of the run before they mutinied. They did eventually eat the egg shells, but not with the same enthusiasm as the oyster shells. I suspect the oyster shells might be salty. Anyway, hopefully they pace themselves a bit more with the egg shells. I also love that it’s free, and I feel sort of accomplished saving the money by cleaning and crushing the egg shells myself, but it does take a bit of work to prep.
How to Prepare Egg Shells to Feed to Chickens:
After cracking an egg shell for cooking or baking, I set it in the sink and when I’m done preparing whatever food I’m working on, I rinse the egg shells and peel off the membrane from inside the egg shell because that membrane makes it difficult to crush the egg shells. Then I set them on a cookie sheet on the counter to dry thoroughly. At first I was baking them in an oven, thinking that killed anything on them, but I read that anything on that egg is something the chickens have already been exposed to, so baking them is an unnecessary step.
I leave it up to you: you can bake them at 35o degrees for 5-10 minute or just let them air dry fully. Once I fill the cookie sheet and the egg shells are totally dry, I crush them by hand.
At first I used a food processor, but crushing them by hand is oddly satisfying and relaxing, lol, so I do it myself now and that way I can better control the size: around 1/4″ or so. Too small, and it will just pass through the chicken without being absorbed. To big, and they could cotton on to what they’re being given. Don’t fret too much about the size of the pieces because if they’re too big, a chicken can easily peck to make it smaller. Just disguise the fact that it is an egg shape and don’t crush into too fine a dust.
But Are Egg Shells Enough Calcium?
I have read, in more than one place, that egg shells are not enough calcium for chickens and that oyster shells are better because they offer a good slow-release source of calcium for chickens. A slow-release of calcium helps ensure a hen has a steady source even when she’s asleep. Keep in mind that it takes a hen 24-26 hours to make an egg, and 18-20 hours of that process is dedicated to the shell formation. So her body is always working on egg production, even when she is asleep and not actively consuming feed or supplemental calcium.
I Offer Chickens Both Egg Shells and Oyster Shells:
Given what I have read, I hope that their feed probably has all the calcium they need – although I do often give treats which may throw off that balance. But because my chickens are a little too addicted to oyster shells, I plan to keep giving them both egg shells and oyster shells to help give them all the extra calcium they need, without letting them gorge too much on oyster shells because too much calcium isn’t healthy either.
Hopefully this helps an new chicken keepers! I am by no means an expert, but I tried to do a lot of research – and a little experimentation – to come up with this plan for my chickens. Just watch the egg shells of the eggs your chickens to help make decisions about their health because their egg shells can say a lot about what’s going on inside.
If chicken keeping is overwhelming, check out these two books that I own and recommend: The Chicken Chick’s Guide to Backyard Chickens and The Chicken: A Natural History.
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