We passed a home and property tonight that had goats with collars.
The word perplexing comes to mind. If you have a goat, why does it need a collar?
To tether it for milking? To tie it to a lamp post when you have walked it to the store with you? To keep it from running into traffic?
I don't know much about animal husbandry, obviously.
;-)
It could also be a collar for the "Invisible Fence." That should work as well for goats as for dogs.
And if you already had it for a dog, then ...