From Halopedia, the Halo wiki

The spadehorn is a bovid indigenous to the planet Reach.[1] A hardy herbivore,[2] the animal named for its pair of flat-tipped spade-like horns. When humans settled Reach, the spadehorn was domesticated.[1]

The spadehorn is the namesake of TurboGen's IWDS "Spade" truck, a vehicle widely used by rural farmers on Reach and settlers on other colonies.[1]

Production notes[edit]

The Spadehorn was originally to appear in Halo: Reach as ambient wildlife. Concept sketches were created for three different varieties of the creature; the Highlands Spadehorn, Prairie Spadehorn and Angelhorn, each with different shaped horns.[3] In Halo Mash-Up: Minecraft Evolved, sheep mobs sport horns reminiscent of the Highlands Spadehorn.