Mine get a Lambivac booster 3 weeks before kidding (I booster every 6 months) and also a separate Ovipast one, again repeated every six months.
I also vaccinated in autumn all females that were to kid against Schmallenberg.
I have last year given them about 6monthly mineral/multivit drenches, but as quite expensive I have not bought another bottle this year. They get a good mix of feed, some garlic/Caprivite/seaweed (not all eat it though..
), plus loads of greenery as soon as available.
Unless yours show distinctive signs of some mineral lacking (and if you suspect vet can bloodtest) and/or of you live in a known area of a specific deficiency they shouldn't need anything in particular.
If the milk tastes awful, they probably could do with a Cobalt/Selenuim drench