Abstract: Milk protein is an important index of milk quality,and the amino acids of milk protein come from the dietary amino acids. Casein,lactalbumin and lactoglobulin in milk protein not only meet the basic nutritional requirements of human body,but also play an important role in human growth development and health. They are the sources of high-quality protein from animals. Methionine and lysine are dietary limiting amino acids of dairy cows. They are not only important substrates for milk protein synthesis,but also signal molecules to regulate milk protein gene expression. In this paper,the requirements and sources of amino acids,essential amino acids, limiting amino acids,protective methionine and lysine in diets of dairy cows were reviewed. The core role of amino acid nutrition in protein anabolic metabolism was expounded,which could provide reference for guiding dietary formulation of dairy cows.

Key words: dairy cows, methionine, Lysine, milk protein, performance