Pack Goat Ban in the Wind River Range

[trail goats]

I have what is probably a dumb question regarding the "penned with domestic goats" experiments that were done.
Where did these goats come from? Was it a closed herd that seemed healthy and had absolutely no prior contact with either domestic or wild sheep in the past?
I know that goats are thought to be "reservoirs" that can pass things from domestic sheep to Bighorn sheep, but I think it's safe to assume that most pack goats don't ever mix with or come in contact with either of the other species.