Iowa law doesn't offer a definite answer. But there have been several court cases which furnish some clues to help determine whether a livestock-share lease adds up to a partnership or remains a simple tenancy.
Arthur, I. W.
"Does Livestock-Share = Partnership,"
Iowa Farm Science: Vol. 7
, Article 3.
Available at: https://lib.dr.iastate.edu/farmscience/vol7/iss6/3