In the wild, baby deer, called fawns, only consume their mother's milk. As they mature, baby deer eat solid plant foods such as grass, leaves and fruits.
If a nursing baby deer loses its mother, it can be bottle-fed with a milk substitute. Goat milk and cow milk are good replacements, but goat milk is recommended. Some retailers carry goat milk or a general wildlife replacement milk that is appropriate for fawns. Older deer need solid food with the formula and can tolerate additions, such as bananas and baby rice cereal. Eventually, the deer weans off milk entirely and eats only plant matter.