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
Sterility is a pathological condition which has been more concisely termed the reduction or absence of fertility. Previously considered by members of the veterinary profession as being a rare occurrence, the problem is now receiving its due share of emphasis as a frequent affection of United States cattle herd sires. The development of artificial insemination with a more intensified form of cattle production in the last decade has brought this condition to the attention of the veterinarian. Formerly, it has been the policy of the farmer to simply discard, or sacrifice for meat, any bull which did not seem to be getting a proper conception rate. Rarely did the owner keep any breeding records to serve as an aid to the practitioner in the diagnosis and treatment of sterility.
Peterson, I. E.
"Sterility In The Bull,"
Iowa State University Veterinarian: Vol. 7
, Article 3.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol7/iss1/3