Intestinal Digestible Protein
Intestinal digestible protein is the measure of the amount of available protein that can be digested by the small intestine. This protein comes from two sources: protein produced in the rumen of the cow (so-called microbial protein) and rumen undegradable protein from feed.
Rumen undegradable protein
Rumen undegradable feed protein is the part of the feed protein that is not broken down in the rumen but passes the rumen as an intact protein and is further digested in the small intestine. Intestinal digestible protein is one of the most important parameters.
There is a direct link between intestinal digestible protein, milk and milk protein production. A shortage of intestinal digestible protein in the ration directly inhibits milk production. Feeding an excess of intestinal digestible protein can (but not always) stimulate milk production. Intestinal digestible protein is strongly linked to plant characteristics, fertilization methods and ensilage methods. Protein-rich plants (e.g. grass and Lucerne) naturally have higher intestinal digestible protein content compared to corn silage or other grain silage. Drier silage often has a higher intestinal digestible protein content, mainly because the protein's resistance is higher. Often, dry silage also provides more energy to the rumen bacteria, allowing them to produce more microbial protein. In dry silage, less sugar is converted to acids to stabilize the silage. These sugars then remain available to the rumen bacteria for the production of microbial protein. A turf in good condition can also contribute to high intestinal digestible protein content in roughage. A good turf with few weeds usually has better nitrogen utilization.