Receiving Rations
Newly arrived cattle recovering from the stresses of weaning and shipment have poor appetites. Under these conditions, highly palatable, largely all-natural protein supplements are preferred to stimulate intake and improve health and gain. Small amounts of urea (less than 0.05 pound/head daily) may be fed in starter diets to adapt rumen microbes to NPN if urea-based supplements are going to be used later in the feeding period.

Finishing Rations
Numerous university studies have shown that virtually all of the supplemental protein in high concentrate diets can be furnished by NPN sources such as urea. Most feedlot nutritionists suggest that urea be limited to about 1 percent of the total ration dry matter, or about 0.2 pound of urea per head daily (0.55 pound of crude protein equivalent) for finishing cattle.

Growing Rations
Once calves have been properly started on feed, urea or other NPN sources such as ammoniated silage can make up most of the supplemental protein in high-quality backgrounding rations. In general, urea can furnish 35 to 50 percent or more of the supplemental protein in silage or hay-based rations containing 4 to 6 pounds of grain per head daily. Generally, supplementing rations with more natural protein ensures optimal performance during relatively short growing programs (less than 100 days), whereas higher levels of urea can be used in longer backgrounding programs. While urea may not be as efficiently utilized as natural protein, the cost differential is enough to justify its use. Research has shown better utilization of NPN when combined with high ruminal escape protein sources such as blood meal, corn gluten meal, and dehydrated alfalfa.

Maintenance Rations
NPN sources are poorly used with low-energy forages like dormant range, crop residues, or hay because they do not contain sufficient readily available energy. Under these conditions, it is generally advisable to use an all-natural protein supplement containing little or no urea.