In order to produce milk, Dairy Cows need to be pregnant every 12 months and give birth.
This is usually done by forcibly impregnating her. A human pushes their arm into her rectum and inserts a long tube of bull semen into her vagina.
To collect the bull semen beforehand, humans arouse the bull using machines until he ejaculates. Or they put a Steer in front of him after he’s aroused, then use an artificial vagina to collect his semen.
This is all done against her will.
(Photo Credit on this page : Jo-Anne McArthur / Animal Equality)