From Academic Kids
Oxen (plural of ox) are cattle trained as draft animals. Often they are adult, castrated males. Usually an ox is over four years old due to the need for training and for time to grow to full size. Oxen are used for plowing, transport, hauling cargo, grain-grinding by trampling or by powering machines, irrigation by powering pumps, and wagon drawing. Oxen were commonly used to skid logs, and sometimes are still in low-impact select-cut logging, in forests.
Contrary to popular American lore, an "ox" is not a unique breed of bovine, nor have any "blue" oxen lived outside the folk tales surrounding Paul Bunyan, the mythical American logger.
An ox is nothing more than a mature bovine with an "education". The education consists of the animal's learning to respond appropriately to the teamster's (ox driver's) commands: in North America such as (1) get up, (2) whoa, (3) back up, (4) gee (turn to the right) and (5) haw (turn to the left).
In addition to intelligence (the ability to learn), American ox trainers favored larger breeds for their ability to do more work; for the same reason, the typical ox is the male of a breed, rather than the smaller female. Also, the gait of the ox is often important to ox trainers, since the speed the animal walks should roughly match the gait of the ox driver who must work with it.
Oxen are most often used in teams of two, paired, for light work such as carting. In past days some teams were about fourteen, and even over twenty for logging. A wooden yoke is fastened about the neck of each pair so that the force of draft is distributed across their shoulders. Oxen are chosen, from calves, with horns since the horns hold the yoke in place when the oxen lower their heads, back up or slow down (particularly with a wheeled vehicle going downhill). Yoked oxen cannot slow a load like harnessed horses can, the load has to be controlled downhill by other means.
Oxen must be painstakingly trained from a young age. Their teamster must make or buy as many as a dozen yokes of different sizes as the animals grow. Ox teams are steered by commands or noise (whip cracks) and many teamsters were known for their voices and language.
Oxen can pull harder and longer than horses, particularly on obstinate or almost un-movable loads. This is one of the reasons that teams were dragging logs from forests long after horses had taken over most other draught uses in Europe and the New World. Though not as fast as horses, they are less prone to injury because they are more sure-footed and do not try to jerk the load. Many oxen are still in use worldwide, especially in developing nations.