Complex sentence: It is not definitively known what this fur rubbing is for, but this may deter parasites such as ticks and insects, or it may serve as a fungicide or bactericide or anti-inflammatory agent.
Split into simpler sentences: It is not definitively known what this fur rubbing is for. But this may deter parasites such as ticks and insects, or it may serve as a fungicide or bactericide or anti-inflammatory agent.