A good-quality, mixed legume-grass hay has generally been recommended Iowa State College results show that high-quality roughage is important with a good starter. Calves did well on timothy but better on alfalfa.
Ratcliff, Lantis; Lambert, M. R.; and Jacobson, N. L.
"What Roughage for Dairy Calves,"
Iowa Farm Science: Vol. 13
, Article 2.
Available at: https://lib.dr.iastate.edu/farmscience/vol13/iss3/2