Tests at Iowa State College indicate that corn silage can replace more hay in the dairy cow ration than is commonly believed. This doesn't mean that college dairy husbandrymen are recommending that dairyman leave all hay from the cattle ration, but corn silage can replace hay to the extent that it's practical and economical.
Porter, A. R.
"How Much Corn Silage in the Dairy Ration,"
Iowa Farm Science: Vol. 5
, Article 8.
Available at: https://lib.dr.iastate.edu/farmscience/vol5/iss2/8