Joan Riley wrote:

Can I just ask (having inherited some hens with the farm) whether the
hens need calcium in addition to the Jondo Flint Chick Grit we have
bought?

Not idea what's in that particular brand, but hens need grit for their
digestive system (it helps grind up food in their crop) and calcium for
egg production. I've seen them sold both separately and together.

Ours get grit, though they probably don't need it that much as they're
fairly free-ranging (for the moment, anyhow) and oyster shell for the
calcium. When I'm using more than an egg or two at a time I also rinse
out the shells, bake a batch of them in the oven when it's on and crush
them in a plastic bag with a rolling pin until the pieces are no more
than a couple of millimetres across. The chickens then get given those
as well.

James