Our vet reccomended Calf Guard, Bovine Ecolizer+C and BO-SE. We live next to a big dairy and our son works there so we pretty much follow what they do just in case of bringing home the diseases they get up there.
We give Alpha-7 & Giardia Lambia and band bull calves as soon as they are dried off. Come back later and use Ultrabac-7 Somnus + Cattle-Master-4 & boost later.