Chickens fed whole grains need to have access to small pebbles or given a product called grit. Grit
is a commercial product made up of small stones. It should not be confused with limestone or oyster shell which is given to laying hens as a source of calcium for their egg shells. Chickens kept on pasture will also require supplementation with grit, though many of them may consume enough pebbles when they forage. Chickens fed only commercially prepared feed do not need grit.