I think it can be, unless it's just to hard to find for you or to high. Another thing you could do is put out bovatec blocks, there not to high and you can just put them out as your only salt and mineral block and they get what they need of the bovatec.
Bovatec has nothing to do with vaccinating. Other than it might help with getting a good take.
And yes it is well worth getting into your calves(and cows before calving).
They have it in minerals but I wouldn't want to count on them eating the right amounts needed(my label says it has to be cut with something else to be fed free choice). I top dress feed with the Bovatec minerals when I start calves. After that its mixed in their TMR.
Bovatec should only add about 20 cents to the cost of a bag of calf starter and is well worth it. Might just look for Deccox (deccoquinate) . Works just as well.