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
Artificial insemination has been practiced in the dairy cattle industry for many years, but in the last few years this breeding technique has found its place in the beef cow herds across the nation. Since 1969 the use of artificial insemination in beef cow herds has increased 3 1/2 times. The key to bovine artificial insemination programs is detecting estrus and getting the cow bred near the end of her male acceptability period. With dairy cattle heat detection is relatively easy since the herdsman comes in contact with the cows in the milking parlor at least twice per day.
Iowa State University Veterinarian: Vol. 36
, Article 3.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol36/iss3/3