Oxfordshire Coat of Arms

The Oxfordshire Coat of Arms, showing a ram, a white horse and a red ox. I have no information on the meaning of these, can anyone help?

Each IBD County Page has or will have (where possible) the relevant Coat of Arms. This is made possible thanks to a fantastic heraldry website called the International Civic Heraldry Website. Sometimes a description is not given due to lack of information, so if anyone could help it would be greatly appreciated. You may visit this superb site by using the link below.