If a feeding program is high in energy, heifers will get heavy or fat. With higher levels of protein (meeting their genetic potential), heifers will grow tall and lay down muscle instead of fat. Excessive protein will be converted to energy, although this is an expensive way to provide energy compared to corn or forage. Thus, the key is the right balance of energy and protein. Minerals and vitamins in excess of requirements will NOT increase gain (no energy in minerals), but if they are deficient, it will reduce growth. All nutrients (protein, energy, minerals, etc.) are provided in the ration or diet.
Mike Hutjens, Extension Dairy Specialist, University of Illinois - Illini DairyNET
