A Bioassay for Determining the Nutritional Adequacy of Protein Supplements for Chick Growth

IN GENERAL, the nutritional quality of proteins depends on the proportion and availability of the amino acids which they contain. Although present analytical methods approximate the amino acid content of proteins, they reveal very little information concerning their availability. Consequently, any true assessment of the nutritional value of proteins must rely on biological evaluation. St. John et al. (1932, 1934, 1944); Almquist (1935); and Heiman et al. (1939) have employed the chick to evaluate the nutritional quality of proteins. However, it should be pointed out that the chick assays cited above measured the extent to which the test protein supplemented other sources of protein in the test diet. If proteins are to be improved by processing or other means it seems necessary to use the test protein as a sole source of protein. Otherwise, its true value is masked by the supplemental effect. A study was undertaken to develop an…