Raw red muscle meat contains around 20-25 g protein/100 g.  Cooked red meat contains 28-36 g/100 g, because the water content decreases and nutrients become more concentrated during cooking.  The protein is highly digestible, around 94% compared with the digestibility of 78% in beans and 86% in whole wheat.  (9) Protein from meat provides all essential amino acids (lysine, threonine, methionine, phenylalanine, tryptophan, leucine, isoleucine, valine) and has no limiting amino acids.  Protein Digestibility Corrected Amino Acid Score is a method of evaluating the protein quality, with a maximum possible score of 1.0.  Animal meats like beef have a score of approximately 0.9, compared with values of 0.5-0.7 for most plant foods.  (10) The amino acid glutamic acid/glutamine is present in meat in the highest amounts (16.5%), followed by arginine, alanine and aspartic acid.  Below the refernces is a page of data for Beef, Veal, Lamb, and Mutton.  Do not pass up the data tables.  The similarities are striking because basically all grass-fed meats are about eh same in their basic nutrient composition.  That's why grass-fed meats are good for us.  Our nutrient composition should match that of all grass-fed critters.