What are the major ingredients in non-protein nitrogen supplements intended for ruminants?

• A. Salt
• B. Corn silage
• C. Ground minerals
• D. Urea or urea phosphate

Answer: (D)

Non-protein nitrogen supplements work by providing nitrogen sources that rumen microbes can use to synthesize their own microbial protein. The major ingredients used for this purpose are urea or urea phosphate, which supply nitrogen in a form readily available to the rumen microbes (urea phosphate also adds phosphate to support microbial activity). Salt, corn silage, and ground minerals do not serve as nitrogen sources for ruminant microbes—salt is a mineral electrolyte, corn silage is a forage providing energy and fiber, and ground minerals supply trace minerals and vitamins. Effective use of NPN requires adequate fermentable energy in the diet and careful management to avoid ammonia toxicity.