Sequence of Limiting Amino Acids in Gelatin for the Growing Chick

Several 6-day growth assays were conducted to delineate the amino acid limitations of gelatin for chick growth. At a dietary level of 14.5% crude protein, gelatin was observed to be severely deficient in nine essential amino acids. Tryptophan, sulfur amino acids and isoleucine were first, second and third limiting, respectively. Aromatic amino acids, threonine and valine were found to be equally fourth limiting, while leucine, histidine and lysine were seventh, eighth and ninth limiting, respectively. Arginine, glycine-serine and proline were observed to be adequate to super-adequate. Rate and efficiency of gain by chicks fed the completely-supplemented diet were such as to suggest rather high availabilities of amino acids in the protein of gelatin.