From The Grey House:
“What does he farm?”
“Humans. And sheep.”
Natalia gave him a look. “For food?”
“Yep. Good cash crop and occasionally, the farmers herd the sheep out where we can get them. Doesn’t happen much as that would kill the crop. Every two weeks, 20 humans from the farms cycle through the house.”
“The vampires farm the humans; the humans farm the sheep and you chase fresh meat every once in a while.”