X2. How often do you move them? Mine are pastured in tractors year-round (it does get more challenging when it's very wet out) - depending on how many are in a tractor, I move them at least daily and sometimes twice a day. I haven't had parasite problems to date; if I did, I'd definitely look at keeping them as dry as possible, try adding probiotics like raw ACV to their water to help them resist infection naturally, and breed for parasite resistance. Parasites seem to flourish in warm, humid environments and are particularly bad when we have a really wet, muddy spring.Try regularly moving your rabbit tractor. The manure buildup is a great breeding ground for parasites.