An ox is a castrated bull trained to work in a yoke. Heavier and stronger than a horse.
Advantages over Horse
Stronger (pulls more weight). Cheaper to keep (eats grass and hay, needs no grain). Calmer (doesn't spook). Split hooves — better on soft ground. No harness needed — just a yoke (wooden, on neck). Meat: when old — becomes beef.
Disadvantages
Twice as slow as a horse. Not suitable for buggy (too slow). Harder to steer (no reins — voice and goad stick only).
Training
Start at age 2. Always work as a pair. Voice commands: Gee (right), Haw (left), Whoa (stop), Get up (go). Yoke introduced gradually — first an hour, then a day. By 3 — working pair.
Uses
Stump pulling (horse can't). Log lifting. Deep plowing of heavy soil. Some communities (Swartzentruber) use oxen instead of horses for everything — even more traditional.