Biuret Applications in Beef and Dairy Rations
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Feed grade biuret, an economical source of non-protein nitrogen (NPN), is an ADM Alliance Nutrition® exclusive. It can be used in ruminant diets and is approved for use in dairy lactation diets. Prior to May 2003, biuret was not approved for use in dairy rations. ADM was instrumental in getting biuret approved for use in dairy rations. Numerous research articles were reviewed and summarized. On May 27, 2003, ADM received an approval letter from the Food and Drug Administration (FDA) allowing biuret to be formulated into dairy rations. Biuret is formed by the controlled decomposition of urea, condensing two molecules of urea into a single molecule of biuret, which retains three of the nitrogen atoms (see Figure 1). Feed-grade biuret is a mixture containing biuret and urea (maximum of 14%) with small amounts of triuret and cyanuric acid. Typically, biuret contains a minimum of 35% nitrogen with a crude protein value of 246% (See Table 1). Biuret is less soluble than urea. The combination of structural and physical characteristics slows the rumen digestion of biuret. The in vitro ammonia release for biuret was similar to that of soybean meal (SBM); whereas, ammonia production from urea was markedly more rapid (see Figure 2; Bartle, et al.,1998). Similar results were observed for blood serum ammonia, when biuret and urea were compared with SBM in beef feedlot diets (Bartle, et al., 2000). The slower release of ammonia from biuret makes it a safe source of nitrogen for ruminants grazing forages and for cattle fed in confinement. The slower degradation and physical properties assist in forming a high-quality, self-fed supplement. Biuret is at least 73 times less toxic than urea, making it ideal when using higher levels of NPN and in self-fed applications. Up to 15 g/lb of body weight of biuret supplementation have not produced toxic effects, while much lower levels of urea supplementation have resulted in death (Table 2 on the next page). Another advantage of biuret is that it is less hydroscopic (attracts less water) compared with urea. Pellets containing biuret are less likely to cake and bridge compared with pellets containing high amounts of urea.

Range Feeding Biuret's slow-release of nitrogen provides a safe and sustained supply of ammonia that is well suited for microbial digestion of lower quality forages. In vitro work conducted by ADM Alliance Nutrition research showed biuret improved cellulose digestion from 36.7% for the controls (no supplemental nitrogen) to 53.78% for biuret. These observations are supported by Loest and coworkers (Kansas State University) who evaluated the effects of non-protein nitrogen on the intake and digestion of steers fed prairie hay. Steers fed a cooked molasses block containing 60% crude...

Dairy Recommendations Nutritional Models: Biuret is unique as a slowly soluble source of NPN. Biuret has a slightly greater ammonia release rate than SBM. Using biuret in NRC 2001 CPM or CNCPS models presents descriptive challenges. As a source of NPN, it fits biologically into the definition of the “A fraction” as a source of ammonia. However, the assumption is made that NPN is immediately available to the rumen, which is incorrect for biuret. The “B fractions” of the models characterize a true protein that supports rumen peptide effects in the CPM and CNCPS models. The “B fractions”...