The suckler cattle get Ivomec Super or Trodax on housing, and any that don't fare well get another dose about 6-8 weeks later.
Trodax can't be used at any time in cattle producing milk for human consumption, to for the house cows we use Ivomec Super injection when we dry them off, at least 60 days before calving. (We're in a flukey area hence using Super not Classic.) Milk withdrawal is 60 days, so that fits in nicely.
If we need to treat them while they are lactating, we use an albendazole product, eg Albex, as that is only 60 hours milk withdrawal.
Youngstock get autoworm or similar on their first season outside after weaning. Older cattle are generally able to handle the resident worms; we aren't heavily stocked.