Download NPN (Non-protein Nitrogen, Urea) Consumed by Horses

NPN (Non-protein Nitrogen, Urea) Consumed by Horses
Ruminant type animals such as cattle and sheep have microbial activity that takes place in the rumen of
the animal before it reaches the stomach and small intestines. These animals are able to utilize ammonia from urea or other non-protein nitrogen sources to synthesize protein, provided that sufficient energy and other nutrients needed are available. The synthesized protein is passed from the rumen to the
stomach and small intestine to be digested and absorbed. Thus, non-protein nitrogen such as urea can
be fed to ruminant type animals to provide them with synthesized protein.
There appears to be no beneficial effect of using non-protein nitrogen in practical diets for horses. As
for horses, microbial activity takes place in the cecum and colon of the horse. Therefore, non-protein
nitrogen is absorbed from the small intestine and excreted in urine before it reaches the cecum and
colon to be used as protein synthesis. That which does reach the cecum and colon may be used for protein synthesis, much of that protein is unavailable to the horse and is excreted in the feces.
Urea is well tolerated by the mature horse at levels up to as much as 4% of the total diet. Research
shows that this tolerance is most likely due to the high solubility of urea, which results in its absorption
from the small intestine and excreted by the kidney. Although ponies succumb to single does of 1.1
pounds of urea, intakes of feed to horses containing 14% protein equivalent from urea (5%) as the total
diet and providing as much as 0.5 pounds of urea daily did not have detrimental effects on mature horses. This amount is several times greater than the toxic amount for cattle. Therefore, horses may be fed
diets containing urea made for cattle. However, the non-protein nitrogen compound in the feed is of
little benefit to the horse. The amounts in these cattle feeds are not harmful.
Since little of the non-protein nitrogen is utilized by the horse, this amount should be subtracted for the
crude protein content of the feed. If the feed tag states that it contains 25% crude protein with 12%
crude protein equivalent from non-protein nitrogen, then the feed provides 13% crude protein for the
horse. The 12% crude protein equivalent from non-protein nitrogen has no benefit or harm to the
horse.