Calcium deficiency is common among high-yielding dairy cows. A calcium deficient cow does not eat much, is cold to touch, looks tired and is unable to stand up. She gives less milk. Untreated cows may die. To prevent calcium deficiency, do not dehorn your cows. Let the cows have some sun in the cool hours, so they will produce vitamin D and absorb more calcium. Feed the cows with legume fodders, maize fodder and tree leaves that are rich in calcium. Give them a mineral mixture in either the drinking water or feed. After milking, give each cow a basket full of green grass. The video contains many other practical tips.