One thing that amazes me is how fast hens go through oystershell, even if you're feeding them a complete ration that theoretically has enough calcium in it. This is probably a good sign, meaning that they are getting some low-calcium nutrition off my pasture and eating less chicken feed.

They had run out of oystershell, and when I took a bucketful out to them today, they fought over it.

That's the thing about nutrition -- it's hard to tell what the chickens lack. You short them on something, and they'll be less productive, but you can't tell by looking.

I recommend providing hens oystershell 24/7, regardless of what else you're feeding them.