Minecraft wiki entry for Things_not_to_do, associated text: Mooshrooms drop 5 mushrooms of their color when sheared, turning them into cows. However, the player can get infinite mushroom stew out of them by right-clicking them with a bowl, meaning "milking" them with a bowl is more efficient. In addition, mooshrooms never grow back their mushrooms when sheared so the player needs to find another one in a mushroom fields biome. If the player has enough mooshrooms to breed them, then shearing extra mooshrooms could be used to get cows and mushrooms. However, if the player plans on killing the mooshroom for beef or leather, then it is okay to shear them beforehand if the player needs mushrooms, as killed mooshrooms do not drop any mushrooms.