Calving is a stressful time in a cow's life, and so we are closely monitoring each cow for signs of distress. We do what we can, with what we have to keep each cow in proper health. Sometimes that means absolutely nothing - she's doing just fine, and we are just checking. Sometimes, it is energy tubes, full of nutrients to keep all her systems functioning at top performance. And, yes, sometimes that does include antibiotics when necessary to clear any infections. (Pushing a 100# baby out doesn't come without some potential issues)
When that happens, we use red duct tape to mark the cow's legs and pull her milk from the milk supply until everything has cleared her system. We have an on-farm tester that allows us to do the testing ourselves.
We are checking all the fresh cows every day for the first 2 weeks after calving, or until we think they are on a solid plan for success. Cows that start off well, will reward us later with not only more milk, but a healthier system that will make her ready for another calf in another year.