Biological Availability of Nutrients in Feeds: Availability of Major Mineral Ions

Abstract

In the study of mineral metabolism, it is generally recognized that the total content of a mineral element in a particular compound or in a complete ration has little significance unless it is qualified by a factor indicating the biological availability of the element to animals. In other words, chemical analysis shows how much of a given mineral nutrient is present, but it does not indicate to what degree, if any, the nutrient is utilized when it is consumed by animals. No element is ever completely absorbed and utilized; some of it is always lost in the normal digestive and metabolic processes. Before a required nutrient can be of nutritional value, it must be in a form that can be digested, absorbed, and transported to the part of the body where it is utilized for its essential function. In the literature there appears to be some confusion as to what constitutes “utilization” and “availability” of the major ions and how they should be expressed and applied in nutrition. Copyright © 1972. American Society of Animal Science. Copyright 1972 by American Society of Animal Science.