I have been feeding my flock layer pellets but have really wanted to switch to grower pellets with oyster shell on the side as most people seem to recommend, especially as I also have one rooster and one younger non laying pullet and at various times someone or other is always brooding or raising chicks. In the UK we don't have all flock feed, only grower or layer plus chick crumbles. However when I try to find oyster shell the vast majority of online retailers only sell mixed grit with oyster shell (I buy all my poultry essentials online as there are no stores that sell the products near me). Now, my chickens free range during daylight hours so they do not require grit and it seems that most of the contents of these mixed grit bags are grit rather than shell so do not seem worth it. Alternatively pure crushed oyster shell is much harder to find and is very expensive. So I was wondering if there is anything else I could provide for calcium, I. E. Some kind of supplement? And when people say oyster shell do they mean the pure stuff or the mixed grit? Another thing I would like to know is how much oyster shell do chickens get through? I have five small bantams and one large fowl hen. If I got a 1kg bag for example how long would I expect that to last? Just a bit unsure here.