If the calves are over 4 to 6 weeks of age, I would not worry, but they will be low on energy and develop a "forage" belly. If they will eat 3 or 4 pounds of a calf starter creep type feed, we would recommend doing this. You may need to limit access to the pasture if they are developing a forage belly, or you may hinder their growth potential.
Mike Hutjens, Extension Dairy Specialist, University of Illinois - Illini DairyNET
