The Mursi tribe in Ethiopia is partly nomad and nourish itself partly from the blood and milk of cows. The Mursi inflict a precise bow and arrow injury to the artery of the cow's throat so they can drink the blood immediately.
Then they cover the wound with dung in order for it to heal. Later, this cow will be "milked" again. The animals are weakened by this procedure and become susceptible to widely spread diseases such as "sleeping sickness". If the cows die, the people are threatened by famine.