Rumen-Protected Amino Acids for Ruminants

Amino acids are required for protein synthesis in mammals. In case of the ruminants, the rumen bacteria can synthesize all of the essential amino acids, theoretically making this animal class independent of a nutritional source. However, for optimal rates of growth in young animals and maximum milk production, the supply of amino acids from microbial protein is limited in both quantity and quality. Therefore, the microbial protein must be complemented with a supply of dietary amino acids in a protected form that is not destroyed by the rumen microbes for maximal productivity. Several methods of decreasing protein and amino acid degradation in the rumen have been suggested by researchers such as heat treatment, chemical treatment, encapsulation, use of amino acid analog, and application of nanotechnology. A number of studies have been carried out to evaluate the potential role of rumen protected (bypass) co-limiting amino acids especially lysine and methionine on growth, lactation, meat quality, reproduction, and metabolic health. This chapter focuses on the significance of rumen bypass amino acids in ruminants, strategies to reduce amino acid breakdown in the rumen, historical developments, and summary of research results along with some practical perspectives about protected amino acid supplementation in ruminants.