Oxen are herbivores, meaning that they eat a diet of plants and grains. Domesticated oxen eat fresh grasses as well as hay and grain supplements. Wild oxen, such as musk-oxen, live in the Arctic tundra and eat roots, moss and lichens.
Domestic oxen begin working as early as four years of age. They are castrated because steers are easier for teamsters to work with than bulls. Wild musk-oxen dig through the snow with their hooves to reach food. They have long, shaggy hair that is well-adapted to freezing temperatures. They live in packs of two or three dozen to guard against wolves.