NRM Oyster Shell Grit - 10kg

Do I have to offer my chickens oyster shell grit if they are on a layer feed?

There is adequate calcium in most high-quality layer feeds to satisfy a laying bird’s calcium requirement and maintain good eggshell quality. However, if birds have access to lower calcium feeds (e.g. foraging or household scraps), providing access to oyster shell grit can be a good idea. Oyster shell grit can also aid gizzard function as it helps to grind up food. This is a bonus but not a necessity, as chickens tend to pick up gritty bits from the environment while free ranging. Oyster shell grit should be supplied ad-lib in a separate container and not sprinkled on top of feed.