beast of burden vs livestock

beast of burden

noun
  • Any domesticated animal trained to perform tasks for humans, such as a herding dog or trained falcon. 

  • A draught animal, such as a donkey, mule, llama, camel, horse, or ox, that carries or pulls a load for the benefit of a human. 

livestock

noun
  • Farm animals; animals domesticated for cultivation. 

How often have the words beast of burden and livestock occurred in a corpus of books? (source: Google Ngram Viewer )