Importance of Dispensable Amino Acids for Normal Growth of Chicks

Abstract

A study was undertaken to estimate the optimal dietary ratio of indispensable to dispensable amino acids (the I/D ratio) for chicks fed amino acid diets. Graded levels of a glycine-proline-glutamic acid mixture were added, at the expense of the basal amino acid mixture, to diets having different total nitrogen contents. Growth results were plotted versus nitrogen level and I/D ratio to produce a three-dimensional figure. Examination of the figure indicated that, under the conditions of these experiments, growth was greatest over a fairly wide range of dietary nitrogen levels when about 33% of the dietary nitrogen was supplied from dispensable amino acids. The results also suggest that gelatin stimulates the growth of chicks fed certain amino acid diets because of its high contribution of dispensable amino acids.