I say this because I just learned a story from a viking saga about the first meeting of the Norsemen with a particular North American Indian tribe, and it was all nice and friendly until the vikings offered the indians a bucket of milk and some trinkets in exchange for some furs. The indians went home and drank the milk but were lactose intolerant and they were all sick. They thought the milk had been poisoned, and so the next day they turned back up at the viking camp spoiling for a fight and the vikings never did establish a permanent foothold on the continental US.
So vikings sailed with live goats/cows???