Abstract
Colostrum and milk of the cow and ewe were assayed for arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine and valine by microbiological methods. The milk protein from both species contained about 1.4 times as much methionine as the protein of colostrum, but only 0.6 times as much threonine. Much smaller differences were noted in the relative proportions of the other amino acids. The amino acid patterns of the milk and colostrum of the two species are very similar.