How can you tell a male nubian goat from a female nubian goat?

Look under their tail and check to see if they have a scrotum with testicles between their back legs - or wait until they urinate if the urine comes from under their belly they are male.

Anglo-Nubian goats were developed in England by crossing British goats with bucks of African and Indian origin.

a billy goat is a female goat

Yes as otherwise the female goats would be pregnant all the time.

I would be very careful about that, because Nubians are 200lbs, but smaller breeds do not mature larger then 115. If they get along well, and are completely out of sight of does, then you can try it,...