Complex sentence: Worldwide, cow's milk, the protein of which mainly comprises casein, is most commonly used to make yogurt, but milk from water buffalo, goats, ewes, mares, camels, and yaks is also used in various parts of the world.
Split into simpler sentences: Worldwide, cow's milk, the protein of which is mainly casein, is most commonly used to make yogurt. Milk from water buffalo, goats, ewes, mares, camels, and yaks however, is also used to produce yogurt in various parts of the world.