Instructions
Research the type of goat you are trying to age. Although most goats continually grow their horns through their first winter, some goats have different horn growth patterns than others.
Look at the baby goat's head. If the buds are barely protruding from the head and are still rounded, it is likely less than 3 weeks old.
Look for a horn bud length less than 3 inches tall. This indicates a kid still in its first year of growth. Once the horns reach about 3.5 inches in length, the goat is no longer considered a kid, but a young adult.
Look at the bud length compared to the size of the ear. Most kid goat horns do not exceed the length of the ear in their first year. The closer the bud is to the length of the ear the further in their first year the kid is.
How to Tell Baby Goats' Age by Bud Size
Most domestic goats are not allowed to keep their horns, being disbudded at less than 3 weeks old. Disbudding, or dehorning, prevents injury to the goat owner and handlers and also prevents fighting among the goats. It is difficult to determine the age of a domesticated goat because of this. However, wild mountain goats keep their horns and can, if looked at up close, be aged very precisely by horn length.