Remember that there are many management choices you can make that can reduce- if not solve- the worm problem in most animals. Rotating pastures frequently, never letting (or forcing) them to eat either manure contaminated grass, or to eat it down tight to the dirt, and feeding hay in racks or feeders, instead of on the ground, makes a huge difference.
If you have a fairly clean herd, and you want to buy a new animal, if at all possible, insist on them being wormed 1 week before you bring them home (with ivomec) and then worm them again 3 weeks later at home. That should get rid of most of the life stages of any susceptible worms.
DE for "worming" goats bothers me especially because I have had so much evidence given to me by a qualified friend that it does NOT work. He's the head pathologist for a major state veterinary lab in a mid eastern state. He told me that of all the goats he's necropsied (thousands), 95% died FROM worms. Not "with" them... the parasite load was the cause of death! And he said "at least half" had a history of either chronic or slug feeding of DE as their "worming" method.
And no, that's not an exaggeration... you can explain it partly because if people are "worming" their goats with DE, they *assume* they can't have parasites. So when they begin to sicken or weaken, they're "sure" it can't be worms. And then they die and they take them to the path lab to find out what "disease" caused it.
Also, NS is correct that it's vital to not overuse wormers, and to rotate between classes of wormers (INCLUDING herbals) frequently, or none of them will work.
And last... folks in the UP are going to have a whole lot LESS trouble with worms in most species than people who live down in the humid south, where the winter temps never get cold enough to break the life cycle of some species. Pasture rotation, and if possible, allowing goats to browse rather than graze, are vital in the warmer climates.
Summerthyme