I only crush the egg shells and put them right back into the feeder. I figure my chickens are out frolicking in the dirt, eating bugs, sand and dirt all day. The egg shells that I feed back to them are cleaner! I crush them by hand until they don't feel sharp and back they go, shell membrane, dried albumen and all. As you can see, the chickens don't seem to complain. I only occasionally supplement with oyster shell when I run out of egg shell. My feed has plenty of calcium, so this is above and beyond. I keep chicken husbandry as simple as possible. Sometimes simple is best! We do cuttlebone and will do eggshells once she starts laying consistantly (she just started so has only given two eggs). I am doing FF and might start sprouting grains too!
I collect egg shells for a week (left in a bowl on a counter) then stick them in the oven for 5-10 min. Grind it in a coffee grinder b4 mixing it with the daily feeds.
