dairy cattle vs dairy cow

dairy cattle

noun
  • cows reared primarily to provide milk; male calves being used for the production of veal 

dairy cow

noun
  • A cow bred for the ability to produce large quantities of milk, from which dairy products are made. 

  • A black-and-white varietal of the Porcellio laevis woodlouse. 

How often have the words dairy cattle and dairy cow occurred in a corpus of books? (source: Google Ngram Viewer )