Recently, we have found a local mill that is making us custom organic feed for our chickens. The lady there is extremely nice and helpful and says she has a degree in nutrition and has been doing this a long time. Her whole job is to design custom feeds and diets for poultry and other livestock. I talked to her the other day about our new feed mix, which I am sharing with someone else who uses it for her layers. I wanted to make sure that she diluted the calcium in it, as she previously said she would, so that it would be safe for my younger birds. And she said to me, "Yes, but you have oyster shells out for your birds at all times, right?" And I said, "Well, no. They're only 12 weeks old. I thought too much calcium before they are laying can be harmful to them." She then told me, "No! You should put it out for them now. Chickens are excellent at self-regulating what they do and don't need nutritionally. If you put them out now, they will be fine and in good shape when they get ready to lay." So, now here I am asking for more opinions on what she told me. It seems to fly in the face of what I read over and over again - that you should specifically NOT give them oyster shells until they are laying. But, she told me that they need them now and won't overdo it. So, now I'm confused.