Mount
A domesticated animal can be used as a riding mount. This requires the animal to be bigger than the rider.
The speed and attacks of the mount will depend on the animal's stats. If the animal can fly, it can be used as a flying mount.
Acquisition
Animals are domesticated at a farm. When a farm is constructed with the purpose of animal-base product, it will automatically fetch a random animal DNA from the environment based on the time of day. The animals will show as belonging to the same empire as the farm, this indicates domestication. These animals can then be freely mounted by any avatar or citizen.
See also: Farming_Mechanics