The biggest 'herd health' step you could take would be to get the cows out of the dry lot and on pasture. The environment they're in now substantially increase the likelihood of you actually needing these vaccines. Contrary to what some believe, 'most' cattlemen aren't vaccinating preweaned calves at all much less running the dam through the chute multiple times per year. Very common for a healthy productive cow to never go through a chute after being weaned herself. My advice would be to get the cows out of the slop to prevent the need for most preventative vaccines, give your replacement calves a 7-way when you wean them-- which will address blackleg something that a cleaner environment won't guard against-- and then only put your mature cows through the chute when there's a problem. You'll be highly surprised how much your herd health increases once you let cattle out of confinement, put them on pasture, and only intervene when there's a visable problem.