Borans are generally more docile and tractable than other Zebu cattle. Large numbers of Boran bulls kept in one herd cause little trouble. Females are easy to handle, although cows with newborn calves can be naturally aggressive when protecting their offspring. Boran cows live long and productive lives and remain sound-mouthed for fifteen years or more. The practical effect of this trait is a low replacement rate of the breeding herd. Bulls are active and fertile until well over ten years of age.