Chickens and ducks need a lot of calcium for egg production. We do feed our birds commercial feed (with no soy or corn), but they also wander and forage a lot around the property. I recently came up with a great way to supplement their calcium intake by giving them eggshells, but disguised so they would not be recognized as eggs and trigger any egg-eating behaviors.
I got a massive box of eggs from a non-profit organization who got them as excess product from a grocery store. With farm fresh eggs in our fridge, I decided to freeze dry the store ones as a way of preserving them for future use. 10 dozen eggs later, I had 120 eggshells in a bucket. I’d wanted to repurpose eggshells and feed them back to the birds for some time but had never gotten around to it, and this was the perfect time. It ended up being remarkably easy, so I figured I’d write it up in case anyone else wants to give it a try.
Don’t bother ensuring your eggs are cleaned out – no need for rinsing or boiling. Just put a whole bunch of eggshells on a cookie sheet and pop ‘em in the oven. Mine were stacked dense and tall, so I knew they would need a while to dry out. I did 250 degrees and ended up leaving them in there an hour and a half. At that point any residual egg whites were browning and dried out, and the shells broke easily by pressing on them with a potato masher.
Once the shells seem dried out and easily breakable, feel free to wait awhile for them to cool. Break them up with a potato masher, and then scoop them into a blender. I did mine in two batches as I didn’t want to overload the blender and make them not circulate well. It doesn’t take long, I went for a course powder texture but you could do finer if you want. FYI, it does create a fine dust in the blender so I let it sit 15 minutes before taking the lid off and pouring the powder into a container.
I don’t know what dosage of calcium the eggshell powder gives, but I stick a scoop (1 tablespoon) in their feed bucket before pouring into the feeder. My 120 eggshells made probably 3 cups of powder. It would be hard to use a blender for a small batch of shells, but if you have a coffee grinder you can dedicate for such things that would work fine. Another option is to store the shells in the fridge for a week or two and let them accumulate, or even longer in the freezer. I’ve heard eggshells are also great in compost blends and for adding to garden soil. I haven’t researched those options but likely will at some point in the future – use the shells however you’d like!