ABSTRACT
Minerals are critical to the normal functioning of essentially all biochemical processes in the body. Optimizing the concentration of minerals in animal diets should generally mean providing sufficient bioavailable concentrations of essen tial minerals to maximize economically important processes such as growth, efficiency of gain, milk production, reproduction, and health (immune function). In recent years, there has been increased environmental concern about the excre tion of minerals by animals. Presently there are few if any restrictions in the United States regarding the concentration of minerals occurring in animal waste; most regulations are directed to land applications of nitrogen. In the future, regulations will likely be placed on the amounts of certain minerals that can be applied via animal waste per unit of land area. Therefore, it is important to define mineral levels and sources that will optimize animal production and mineral losses in urine and feces.
