Fresh or sour milk is a valuable feed. Put it in plastic, glass or enamel containers, as the lactic acid formed will rust galvanized containers. If chickens are fed whole grain or green forage, they should also receive insoluble grit. Grit is available in chick or hen size. Continuous feeding is not necessary, but grit should be available free choice, two or three days per month.
Fine gravel is an acceptable substitute for purchased grit.
Laying hens require large amounts of calcium for egg shells. An effective way to provide it is by free-choice feeding of oyster shell or calcium grit. Also, egg shells can be saved, washed, dried, crushed and fed back to the hens. Wet shells should not be fed because there is a danger of bacterial growth on the residual albumen. There is also the risk of induced egg eating.