Goat and kids recognize each other by the sound of their calls, not by their appearance.

Goat and kids recognize each other by the sound of their calls, not by their appearance. Kids suckle for a period of six months, before they begin to eat leaves and grass. Their age can be determined by their teeth. A one-year-old kid has, for example, two teeth, while a two-year-old has four teeth and is then considered adult.
Fun fact

Newly born domestic goat kids are able to stand immediately and to follow their mother.