People will tell you that layer feed it made to have enough calcium and you don't need to offer anything on the side. However, the amount of calcium in layer feed is based on the average amount that an average chicken will need. For example, they study 100 chickens and calculate the amount of calcium that each chicken uses, then averages it and say that is the amount that a chicken needs. However, there are some chickens who use more, some who use less - that is why they take an average.
I was getting a number of soft shell eggs from my first flock of chickens. I feed layer feed and thought that would be good enough. When I added a dish of oyster shell to their coop, within 2 weeks the soft shell eggs were no more. 3 years later and I am still on the same bag of oyster shell, so they really didn't need much more calcium, but some did need more and ate what they needed.
Having oyster shell on the side is especially important if you have roosters in the flock. If you have roosters, you should be feeding an all-flock so there isn't too much calcium for the boys. With oysters shell on the side, the ladies can pick up extra calcium as they need it.
I was getting a number of soft shell eggs from my first flock of chickens. I feed layer feed and thought that would be good enough. When I added a dish of oyster shell to their coop, within 2 weeks the soft shell eggs were no more. 3 years later and I am still on the same bag of oyster shell, so they really didn't need much more calcium, but some did need more and ate what they needed.
Having oyster shell on the side is especially important if you have roosters in the flock. If you have roosters, you should be feeding an all-flock so there isn't too much calcium for the boys. With oysters shell on the side, the ladies can pick up extra calcium as they need it.