Good hog men have always preferred to feed animal proteins such as meat and bone scraps, tankage and fish meal rather than plant proteins such as soybean oilmeal. Animal proteins cost more than plant proteins and have been harder to get. Why do good hog men want animal proteins?
Catron, Damon and Culbertson, C. C.
"Faster Gains With APF,"
Iowa Farm Science: Vol. 3
, Article 2.
Available at: https://lib.dr.iastate.edu/farmscience/vol3/iss11/2