Part 7: Body Conditioning Score Series: Protein Management
When considering feedstuff selection and ration development, producers often base decisions heavily on protein content of the particular feed or feedstuff in question. For purposes of this article, we will define a feedstuff as any component of an overall ration being fed to cattle (e.g. Bermuda grass hay, corn gluten pellets, cottonseed meal, ryegrass baleage, etc.) Whereas a feed is a combination of feedstuffs that make up a ration. Producers and veterinarians alike often describe particular feeds or feedstuffs by their protein content (e.g. “The feed I purchased is a 14% feed). Protein is also often the most expensive component in the diet of beef cattle, making an understanding of efficient protein use critical to the cow-calf producer.
Crude protein in a feed or feedstuff is basically a measure of its nitrogen content. In ruminants, crude protein can then be further divided into two broad categories: 1.) Rumen degradable protein (also called degradable intake protein, or DIP), and 2.) rumen undegradable protein (also called undegradable intake protein, UIP, or “bypass protein”). Both types of protein are essential to the proper utilization of nutrients by the cow. Rumen degradable protein (DIP) is the portion of protein in the feed or feedstuff that is used by the microbes in the rumen to break down digestible fiber releasing energy and protein-breakdown products that are then used by the cow. Rumen undegradable protein (UIP) is protein that “bypasses” the microbes in the rumen and is digested and absorbed directly by the cow in the small intestine.
When feeding cattle, you are actually feeding the microbes in the rumen, and sudden alterations to the microbial population can have severe effects on health and productivity of the cattle. When cattle are on a forage-based diet, rumen microbes break down fiber into energy that can be used by the microbe and by the cow. These microbes require protein to function, and if protein is limited in the diet, there is a direct limitation on the fermentation and breakdown of fiber in the rumen. Cattle on a high forage diet therefore, need protein to digest the fiber from forage.
The information in this article as well as additional information on ruminant digestion can be found at the following source:
Parish, J.A., Rivera, J.D., Boland, H.T., Understanding the Ruminant Animal Digestive System. Mississippi State University Extension Service. Publication 2503. 2017. http://extension.msstate.edu/sites/default/files/publications/publications/p2503.pdf