Brad is right. Oxen teams have either a head yoke or a neck yoke depending on where you are in the world. New England used mostly neck yokes, with maritime Canadians often using a head yoke. Horse collars have been used on oxen, but it was not a standard practice. The oxen yokes are apparently much quicker and easier to harness compared to a horse harness assembly. Horse wagons have a higher maximum speed than oxen, so are strongly favored when you have to move artillery fast, but for the long long haul, oxen have advantages.
in the days of European siege warfare, 16th and 17th centuries, thousands of oxen would be employed to move an artillery train:
From Duffy (Fire & Stone):
In 1697, by when artillery was much lighter than it had been in the early 16th century, the Austrian general Borner made some calculations for a projected siege of Temesvar, and decided that he would need 1,849 pair of oxen and 753 vehicles to transport a small train of ten 24-pounders and ten mortars and the downright inadequate stock of 3,000 roundshot and 2,000 bombs.
I understand that the British (Wellington?) used oxen to haul artillery in Spain.