Ox

From Conservapedia

An ox (plural oxen) is a domesticated bovine that has been trained to pull loads and follow commands. A variety of animal species serve as oxen in different parts of the world. Oxen are typically slow but have great endurance and durability.

Both male and female animals can be used as oxen, but castrated males are normally used as they are larger and stronger than females but not as aggressive as intact males.