You may want to do some research on the affects of feeding high levels of calcium to Males, Young Birds and Non-Laying Females.I have 14 chickens and 2 ducks. Male female ducks. 2 of the chickens are roos. THEY all get layer food. Shell are a waste of money. Layena has it all in it. Why pay for extra and double the work. I never ever had a problem with the chickens or ducks. Egg shell, again, never had one to break because of softness due to lack of calcium. Same goes with grit. Never once have I bought a bag of grit. Our land is so full of rocks. They scratch for there own grit.
Males, Young Birds and Non-Laying Females only need about 1.5% calcium in there diet and any more than that is doing harm and can kill the birds.
Now before someone says that they feed layer to everyone and never had a problem I will say this, There is a good reason for Calcium Toxicity being called a Silent Killer.
Chris