Amino acid composition and nutritive value of goat milk casein.

Abstract

Summary1. Casein from goat milk was prepared by isoelectric precipitation followed by ether extraction. Amino acid composition was determined by chromatography on Dow-ex 50 ion exchange resin. The nutritive value of goat milk casein was determined by a rat growth assay method. 2. Goat milk casein has a higher content of glycine and lower concentrations of arginine and methionine than the values reported for cow's milk casein. The earlier reports on goat milk casein did not include values for glycine, isoleucine, methionine or threonine. 3. The biological value of goat milk casein, as prepared in our laboratory, is similar to that of commercially available cow's milk casein. The cow's milk casein prepared in our laboratory, however, had a somewhat higher biological value than either of the other two samples. 4. These differences in amino acid composition may be the basis for the differences in biological value of caseins from goat and cow's milk.