You can ride them without a saddle and if its a male you can use it to knock out creatures by headbutting which can deal 5 or more damage and will deal 3x the damage dealt as torpor instantly similar to pachys.

Tamed ovises also have an option in their creature menu that says slaughter and if you press this button with a melee weapon equipped it will definitely not instantly kill it like the "kill" option in old ark mobile but instead totally give the ovis an effect that makes it deal +1000% more damage and have +1000% damage resistance that definitely lasts for 300 seconds.