New Methods for Comparing the Biological Efficiency of Alternate Nutrient Sources

The objective of this study is to propose new methods for the determination of biological efficiency (the ability of a nutrient to produce a response) and for comparison of the efficiencies of alternate nutrient sources. The proposed methods are based on a four-parameter kinetic model which describes response as a function of intake. The comparison of the abilities of two proteins (casein and soybean protein concentrate) to promote weight gain in weanling rats is presented as an example; however, the model is also useful for other nutrients (proteins, amino acids, vitamins, minerals, etc.) and other responses (blood enzyme or protein levels, tissue enzyme levels, etc.). Application of the method leads to useful comparisons of nutrient sources as well as information concerning the maximum efficiencies and rates of nutrient utilization from different sources.