We give pre breeding and pre calving shots. Calves receive vaccinations approx 2 weeks after last calf is born for that season - modified live , again at weaning and again at yearling. Next set are given at breeding/calving seasons.
You may get buy without vaccines for a long time, but sooner or later it will catch up to you, like the farm that didn't think it necessary to vaccinate their AI sire/herd bull - died from pneumonia!! Could have been prevented with vaccine.
Valerie