feed costs, non-protein nitrogen, ruminant rations
What is non-protein nitrogen? All proteins contain nitrogen, but not all nitrogen is contained in proteins. For example, urea and anhydrous ammonia are two compounds which contain significant amounts of nitrogen, but neither is a protein. Instead, they are called nonprotein nitrogen (NPN) compounds.
Cassel, E. Kim, "Using Non-Protein Nitrogen to Control Feed Costs" (1996). SDSU Extension Extra Archives. 107.