colostrum vs first milk

colostrum

noun
  • A form of milk produced by the mammary glands in late pregnancy and the few days after giving birth. Human and bovine colostrum is thick and yellowish. In humans, it has high concentrations of nutrients and antibodies, but it is small in quantity. 

  • A mixture of turpentine and egg yolk, formerly used as an emulsion. 

first milk

noun
  • colostrum; beestings 

How often have the words colostrum and first milk occurred in a corpus of books? (source: Google Ngram Viewer )