Limited results indicate that grass silage probably can fed to milking cows without loss in milk production or body weight. Here are the reults of a comparison study made at Iowa State College last year.
Porter, Arthur R.
"Grass Silage as the Only Roughage for Dairy Cows,"
Iowa Farm Science: Vol. 7
, Article 5.
Available at: https://lib.dr.iastate.edu/farmscience/vol7/iss9/5