While dairy farming is terribly cruel, artificial insemination is not rape

Before a dairy cow is artificially inseminated, she has to show signs of mating desire. A farmer will notice his cows mounting each other. It is known as “bulling”. He then calls the artificial insemination officer at the local sperm bank where a suitable sperm is selected from the hundreds available. The sperm is delivered via a long glass tube, inserted into the cow’s vagina by a trained officer and guided by his arm. The operation is only carried out when a cow is ready for mating since conception would not take place otherwise. So while it is artificial it is not rape but perhaps better termed “consensual”. 
Artificial insemination does have some advantages. The sperm donors are healthy strong bulls with a known pedigree. Were a farmer to keep his own bull to service his cows, the whole herd could become genetically weakened by incest. In the wild, bulls fight for the right to service the females. In this way, as with other species, the continuance of the species is ensured genetically with continual fresh young sperm from the strongest males. This is not possible with a domestic herd of females so artificial insemination replaces the ongoing struggle between bulls. The donors do not fight but peacefully donate their sperm.
While the whole notion of dairy farming is hideously cruel and totally unnecessary for human nutrition, artificial insemination, professionally carried out, is not rape. 
My comments are based on hands-on experience.
JC Wilcox