Animals two years or older are difficult to separate by size, although full adult growth isn't reached until about four years of age. Adult males average about 150 pounds but may reach weights as high as 300 pounds. Adult females average about 125 pounds with a maximum weight approaching 250 pounds. Body size alone is not a reliable indicator of a goat's sex and can be used only in combination with other characteristics when judging trophies. How to Judge Trophies by Horn Size and Appearance Horn lengths are approximately the same in male and female goats of the same age.
Kids grow only short buttons up to one inch long during their first fall.
By the time a goat reaches the yearling age class, it has attained over half its expected horn length. Most yearling goats have horns about six inches long, which at a casual glance look much like adult horns. By the time a goat is four years old its horns are 8-9 inches long. The world' s record mountain goat, a male killed in British Columbia in 1949, had 12 inch horns. Although horn lengths are difficult to discern, other horn characteristics can be used to differentiate between the two sexes.