Dr. Kamlet also used a "non-protein nitrogen supplement" in feeds and fodder.

Melamine use as non-protein nitrogen (NPN) for cattle was described in a 1958 patent.

It also mentions in passing the product makes use of "NPN" which is an acronym for non-protein nitrogen.

Non-protein nitrogen (others)

Biuret is also used as a non-protein nitrogen source in ruminant feed, where it is converted into protein by gut microorganisms.

FDA permits a certain amount of cyanuric acid to be present in some non-protein nitrogen (NPN) additives used in animal feed and drinking water.

There is at least one report of inexpensively priced rice protein concentrate (feed grade) containing non-protein nitrogen being marketed for use in non-ruminants dating back to 2005 .

Nitrogen compound overload: Herbivores are equipped to deal with a normal level of potentially toxic non-protein nitrogen (NPN) compounds in their forage.

To ensure food quality, purchasers of protein meals routinely conduct quality control tests designed to detect the most common non-protein nitrogen contaminants, such as urea and ammonium nitrate.

Accidental contamination and intentional adulteration of protein meals with non-protein nitrogen sources that inflate crude protein content measurements have been known to occur in the food industry for decades.

High-quality feed block or HQFB, is a solid block consisting of molasses, non-protein nitrogen (NPN), rumen by-pass protein (cassava hay), minerals and lipids.

Ruminant animals can obtain protein from at least some forms of non-protein nitrogen (NPN) through fermentation by their rumen bacteria, hence NPN is often added to their diet to supplement protein.

It is not clear from that report whether the contaminant in that case was melamine or some other non-protein nitrogen source or whether any contaminated rice protein concentrate made it into the food supply at that time.

Non-protein nitrogen (or NPN) is a term used in animal nutrition to refer collectively to components such as urea, biuret, and ammonia, which are not proteins but can be converted into proteins by microbes in the ruminant stomach.