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
During the last summer many pork producers were looking for ways to lower their feed costs. Those feeding a complete supplement probably ran into some problems if they eliminated or severely reduced the supplement without replacing the vitamins and minerals, particularly calcium and phosphorous. In addition to reduced growth rate efficiency they may even have experienced poor bone development or possible fractures.
Holden, Palmer J.
"Low Protein for Growing-Finishing Swine,"
Iowa State University Veterinarian: Vol. 36
, Article 6.
Available at: https://lib.dr.iastate.edu/iowastate_veterinarian/vol36/iss1/6