A “niun” is a large, very ugly cow-like creature that serves as a beast of burden.  It has short tusks instead of horns, and is capable of intense bursts of energy.  Most are docile, but I have also seen them become quite formidable when provoked–they can stick those tusks in all sorts of inconvenient places.  A niun appears to be something between the ox and the boar of your land.