I was searching online about egg shell nutritional values and it says calcium is 90%. Is there any reason I cant grind up egg shell in to a powder and put on my torts food as a calcium supplement instead of buying calcium?
No reason at all. I'd boil them first. I fed a bunch of duck, chicken and geese eggs last night. I boil them and just kinda crack the egg all around then feed. However for an animal that doesn't really need any protein in their diet I'd just feed the shells and not the whole egg.