As Jeanne said, it gets costly if you have alot of cattle.
If you live very rural, most infected wildlife die in the woods where they live.
However, if you live on the fringes of a busy city/town where there are alot of urban raccoons, etc, eating trash and causing problems--that is a different situation.
My suggestion:
If you have just a few head and are in a hot area for rabies and are having the vet come out for something else--might as well have him do your cows.
Your state lab has a list of where all the rabies positive animals were found. If there are locations listed that are within 5 miles of you--vaccinate.
Several of my cows were originally pastured in a hot rabies area in another state. Several cats came up positive within a mile of where my cattle were, so I had them vaccinated.
I slept better at night.
It paid off 3 months later, when a neighbors cat also came up positive. His entire herd and his horses were put under quarantine. He couldn't move, sell or show anything for 6 months and they euthanized all his other cats-and one beloved unvaccinated dog-- for testing.
The $$ he would of spent on rabies vaccinations was tiny compared to the financial ( and emotional ) fall out from not vaccinating. He now has several acres for sale on his once unsubdivided property.