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
Previous to the first World War, poultry production was limited largely to relatively small flocks. Poultry and eggs were primarily a farm by-product. Each farm flock was self sufficient. No outside breeding stock, commercial feed, or complicated system of marketing was involved in poultry production during the prewar period.
Norton, R. E.
Iowa State University Veterinarian: Vol. 5
, Article 5.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol5/iss4/5