This seen as a symbol of strength, toil, wealth and sacrifice and in some traditions, it is a symbol of interchangeable with the bull. Though it is castrated it does not share the fertility sign of the bull. According to the Roman writer Varro, it was a crime to kill an ox throughout Attica and the Pelopennese. Only in dire emergencies that the ox would be sacrificed and even this was a crime so a scapegoat would have been used instead. Alternatively, the knife used in the killing would be throwing away or destroyed. In Chinese myth, Nui Wang god of oxen protects the creatures against epidemics and is associated with the spirit of the star Tien-wen. Hadhayosh is the great ox of Zoroastrian mythology. It carried the first humans across the ever-pure sea, Vourukasha. When the Frashkart or end of all things comes, it will provide the fat that will help make the immortal drink of haoma.
John and Caitlin Matthews, The Element Encyclopaedia of Magical Creatures, 2013, Ox, p 360