Urea and ammonia poisoning in ruminants: A brief overview

Pasture and crop fields, urea is used as a fertilizer. In snow-covered residential areas, it is occasionally used as a substitute for common salt to melt snow and ice. However, during World War II, it began to be used as a low-cost source of non-protein nitrogen (NPN) in the diet of ruminants. When combined with enough other feeds, urea is significantly more tolerable. Urea can be added to the whole feed (on a dry weight basis) in amounts of 2 to 3 percent without causing toxicity