Low Cost Cow/Calf Program

The Bulletin For Alumni Of The School

Volume 9 Number 3
Non-protein Nitrogen

Urea is manufactured synthetically by reacting natural gas, atmospheric nitrogen and water – together, at high temperature and pressure – to produce ammonia and carbon dioxide. About 78% of air is nitrogen. These gases then are reacted at

Urea 46% N

high temperature and pressure to produce molten (liquid) urea. This then can be cooled and made into granules or prills. The liquid form of urea is used mostly in fertilizer mixtures, with only a tad going to liquid feed supplements. Solid urea is used in fertilizer, feed supplements and plastic manufacturing. Only about 3% of the urea is used in animal feed and about 12% in plastics–the remainder goes to the soil. Drying the urea liquor in a drum dryer or over a fluidized bed produces urea granules. Urea prills (BB’s) are formed in a prilling tower. The tower has a shower nozzle at the top, which is where the liquid urea is sprayed into a counter flow stream of air. Desired prill size is achieved by tweaking on the flow rates of the urea and the air. It is not unlike the formation of hailstones. Generally, granules are larger than prills and are the choice of the farmer. Large prills also go into fertilizer, while smaller prills are used in ruminant animal supplements. This is especially true for mineral supplements offered ad libitum. The supplement manufacturers make every effort to have all ingredients of similar particle size and angles of repose. Segregation of the various ingredients is a definite no-no. A urea spec sheet generally states the amount of biuret present. Taking the urea formation step to a higher temperature, a higher pressure or for a longer amount of time forms

Biuret 41% N

Biuret. Urea is highly soluble, while biuret is only slightly soluble in water. The farmer wants the next rain shower or irrigation to put the urea into the soil. Therefore, biuret is considered undesirable. In part, because of its solubility, urea is degraded rapidly to ammonia in the rumen. Conversely, biuret is degraded slowly to ammonia – in part because of its relative insolubility. Several studies have shown the rate of ammonia formation in the rumen from urea vs. biuret. Biuret is slow release.

A Feeding Study

Oregon State U supplemented fescue straw diets, fed to 1200 lb cows in their last trimester, with either urea or biuret. The chemicals made up only 18% of the supplemental degradable protein. The rest came from soybean hulls. The supplements were fed either daily or on alternate days. The alternate-day level of supplement was double the daily level. The treatments were non-supplemented control (CON), urea-supplemented daily (UD), urea on alternate days (U2D), biuret daily (BD) and biuret on alternate days (B2D). Performance data are shown in the following table. The urea-containing supplement (1.5 lb UD and 3 lb U2D) contained 91% soybean hulls, 3.7% dried molasses and 5.3% urea. Similarly, the biuret-containing supplement (1.6 lb BD and 3.2 lb B2D) was made up of 90.2% soybean hulls, 3.7% dried molasses and 6.1% biuret. The CON cattle were not fed a supplement. One must wonder if the study was about soybean hulls vs. no hulls, rather than a comparison of the two NPN sources. At any rate, the non-supplemented CON cattle did not fair very well compared with those groups that were fed a supplement. As far as the urea vs. biuret, there was no difference. The same can be said for the feeding of supplements daily or every other day. A true evaluation would necessitate the feeding of urea and biuret at much higher levels. This has been done in other studies. When the urea level is high enough that cattle performance falls off, biuret cattle continue to perform. ADM/Moorman’s has an exclusive with the biuret.


I took Dick Diven’s course a few years back. Then we took forage samples and Dick helped us make a mineral and salt mix for our cattle that works better than any commercial mineral or kelp that we had ever tried and it was way less expensive. We seem to have a lot less eye and foot problems. We purchased some cows a couple of years ago and it took a year of being on this mineral before they had less problems too. This course has well paid for itself from the knowledge we gained.

Thanks, Allen Powell …Missouri

Schools In 2004

Kehoka, MO August 2 — 5

Bozeman, MT November 1 — 4

Lacombe, AB November 9 — 12

Elko, NV December 6 — 9

Dick Diven

Agri-Concepts, Inc.

12850 N Bandanna Way-Tucson, AZ 85737

800.575.0864 or 520.544.0864