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
Sheep husbandry in the United States may be divided in a general way into three classifications-farm flocks, the range sheep business, and the feeding industry. From the standpoint of the control of disease, the important diseases and the methods of control differ in these three main subdivisions of the industry, although of course there are many disease problems that are common to all sheep operations. Although the diseases of major significance in the range states differ to some extent from those of the feeding and farm flock areas, a very large percentage of the sheep produced in the range states sooner or later lands in the feed-lots or farm flocks of the central states. The wether lambs and part of the ewe lambs from the range are shipped to the feed-lots. The range breeders sell their 6-year-old ewes either into the feed-lots or to the farm as breeders. Therefore, the feeders and farmers of the corn country are concerned with the health of the sheep of the range country.
"The Relation of Disease in Range Sheep to Sheep Feeding in the Corn Belt,"
Iowa State University Veterinarian: Vol. 7
, Article 2.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol7/iss3/2