Where rabbits get worms is still somewhat of a mystery of me. I've had one case of pinworms and I don't know how she got them. My rabbits are all up off the ground and that's where the worms are. But as my vet said, they can get them if there's been fecal matter on the ground and you've put something on or around the dropped bunny poo..it just happens...I know of one lady who kept her Angoras in an enclosed front porch and her meat rabbits outside, her husband put his muddy work boots next to the Angora cage after he had been working with the outside rabbits...Yup, the Angoras wound up with pinworms--I've never gotten a clear cut answer as to where they come from; Not even from the ARBA higher ups.
Managing a group of rabbits like yours is a bit different than taking care of a few, you'll need to establish a preventive plan. At the end of winter I usually worm if I suspect any problems and then and I put all the rabbits through a stint of sulfaquinoxaline--brand name Sulmete-- followed by an An Acid 4-Pak. Any problems I've had with parasites has always happened after winter...maybe because they're closed up for the winter. I don't know. Side note to this though! If I notice soft or pasty droppings at anytime and I know that feed is not the problem, I'll start a round of Sulmete. Coccidiosis needs to be dealt with before it starts spreading in the bunny herd. Right after Spring begins I give out a dose of Ivomectin--now before anyone gets into an uproar, yes I know it hasn't been approved for rabbits, but I also know every breeder I know uses it and we're able to control fleas and mites through out the summer. And none of us have lost a rabbit one due to Ivomectin. Note of caution though--never give meds to a pregnant or lactating doe. I will generally do all the preventive steps prior to breeding my does and the bucks I've chosen for them--or I'll wait until baby bunny season is over. The bottom line is that you have to safeguard the animal's health in order to get that glossy soft Angora wool
This is a link that will tell you how much you need to give your bunnies for worms. For pinworms, you'll need something with Piperazine to get rid of the problem. If for some reason your bunnies don't improve after giving them the meds for pinworms, I'd go to the vet. I'm not a vet...I can only share what I've experinced.
http://homepage.mac.com/mattocks/morfz/rx/drugcalc.html
Acid 4-Pak is a probiotic, it replaces all the good flora in the bunny's intestine and also loaded with electrolytes and vitamins. Just follow the directions on the package and you'll be fine. If you can't find it at your feed store, you can order it (and just about anything else bunny related!) from
www.bunnyrabbit.com
Since you're new to rabbits I would suggest checking into these sites...They're loaded with great info. Both authors are top Angora breeders.
http://home.pacbell.net/bettychu
http://www.angorarabbit.com/angora-rabbit-manual
And I would recommend getting a copy of Completely Angora. It's more or less the Angora breeder's Bible
Sorry to go on so long....hope it helps...
Suzi