It is suggested that calves should be consuming a minimum of 2 lb/day of a high quality calf starter before weaning. Calves can be maintained on the starter for 2 to 3 weeks postweaning and then transition to a grower diet offered with long forage. The end product of microbial digestion of forages is primarily acetic acid. The microbial end product of grain (starch) is propionic and butyric acids. Butyric acid is the one VFA (Volatile Fatty Acid) that directly supplies the rumen wall with energy. Therefore grain should only be fed before the rumen is well developed. Then they can better digest forages.
Dave Fischer, Extension Dairy Educator, University of Illinois – Illini DairyNET;
Jim Paulson, University of Minnesota, Regional Extension Educator, Dairy
Arlyn Heinrichs, Dairy Extension, Penn State University.