Intestine digestible amino acids
Definition
Intestine digestible amino acids are amino acids available at the gut level for use in maintenance, growth and production.
Importance
The microbial protein produced in the rumen is the largest supplier of intestinal digestible amino acids and contains a favorable amino acid pattern for milk protein production.
Intestinal digestible protein in high-producing cows
In high-producing cows, a growing proportion of intestinal digestible protein comes from rumen-undegradable (resistant) feed protein. This shift increases the importance of amino acid balance in the diet.
Limiting amino acids
Among these amino acids, lysine and methionine are typically the first-limiting for milk protein synthesis. In rations based on grass silage, histidine can also become limiting.
Supplementing methionine—often in combination with lysine—primarily improves milk protein content, with a smaller effect on overall milk yield.
Calculation of digestible amino acids
The amount of intestinal digestible lysine and methionine is calculated using the same principles as the intestinal digestible protein fraction, ensuring accurate formulation for optimal production.
