Iowa State University Veterinarian Records, RS 22/6/0/9, University Archives, Special Collections Department, Iowa State University, http://www.add.lib.iastate.edu/spcl/arch/rgrp/22-6-0-9.html
The artificial insemination of dairy cattle was introduced into Iowa in 1942 in the areas near Cedar Rapids and Kanawha. At that time around 3,000 cows were bred artificially and the program has grown steadily until in 1948 120,000 cows were bred artificially in the state.
Herrick, John B.
"The Artificial Insemination Program In Iowa,"
Iowa State University Veterinarian: Vol. 12
, Article 6.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol12/iss1/6