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A Little NPN Goes A Long Way

Most Cattlemen are aware of two types of protein supplements.  Those that are called an “all-natural”1, and those that utilize some urea, or other form of non-protein nitrogen (NPN).  It is not unusual for Cattlemen to hesitate, or outright refuse to use a supplement containing NPN.  Instances of overconsumption with free-choice supplements containing NPN have occasionally caused animal deaths.  This is usually due to a combination of environmental factors (e.g., forage or water availability), and often times it is exacerbated by the previous plane of nutrition of the cattle involved.  Still, many cattle are safely and effectively supplemented each year with a supplement containing some NPN.

You may have heard that with a ruminant animal, you do not feed the animal, but rather, you feed the microorganisms in the rumen, and they in-turn feed the animal.  This is true to a large degree with the protein needs of beef cattle.  Aside from a few key amino acids, what beef cattle really need from protein in feeds and supplements under most production conditions, is the nitrogen (N).  This N, along with some energy (e.g., molasses in a supplement block), is used by the microorganisms in the rumen to reproduce, while they digest the forages the animal consumes.  The microorganisms are eventually flushed out of the rumen, into the small intestine, where they are digested, providing protein and some energy to the animal.  The key here, is that, the microorganisms in the rumen can just as easily use N from NPN as they can from true proteins.  The value to Cattlemen, is that N from NPN is much cheaper than N from true proteins.  Under many grazing systems maximizing rumen function is first and foremost the limiting factor in cows maintaining body condition because it is so critical for extracting energy from the forages as well.  If the rumen microbes are starved for Nitrogen, fiber fermentation stalls out and conversion of forage to body condition or growth in beef cattle is limited.  This is the proverbial “low-hanging fruit” that Cattlemen must make sure is optimized before going further in evaluating the nutrition program.

Ridley Block Operations recently conducted an experiment to evaluate the differences in ruminal digestion of forages by an all-natural supplement, and 2 supplements containing some NPN.  The experiment was conducted in an artificial rumen called a continuous culture fermenter. 

The treatments were as follows:

  1. Low quality Hay as a control
  2. Treatment 1 plus a 25% all natural protein supplement
  3. Treatment 1 plus a 25% protein supplement with 14% NPN.  The majority of the natural protein in this supplement was from distillers dried grains with solubles.
  4. Treatment 1 plus a 25% protein supplement with 14% NPN.  Some of the natural protein in this supplement was from soybean meal.

Digestion coefficients for the four treatments are shown in the table below.

While the only statistical difference between treatments was for digestion of non-structural carbohydrates (NSC), dry matter, organic matter and neutral detergent fiber (NDF) were numerically higher for the two supplements that utilized some NPN.  Does this mean that the supplements with some NPN are superior to an all-natural supplement?  Perhaps not, but, I believe it does show that they are, at the very least, equal to an all-natural supplement, in terms of ruminal forage digestion.

As I stated earlier, not all Cattlemen will be comfortable using a relatively lower cost supplement containing some NPN, but those of you that are, rest assured,  you are using a supplement that is every bit as good as a supplement that is touted as being an “all-natural”

The protein by-product ingredient market conditions have been increasing due to drought across much of the US.  This will make the manufacturing of “all-natural” protein supplements very costly.  Selecting free-choice supplements that have controlled intake minimizes the risk of over-consumption when NPN is formulated in to help reduce costs of your nutrition program.  These results support the use of NPN as a portion of the protein being supplemented on lower quality forages and the economic advantage for doing so may be even more convincing given the current prices in protein meals.  We would encourage you to consider this option when planning your supplement needs.

1 The term “all-natural’, as used here, and in the feed industry for decades, has more recently been confused as a supplement intended for use with cattle in a “Natural  Marketing Program”.  The two are not interchangeable.  It is entirely possible to have an all-natural supplement that contains allowed animal proteins (e.g., feather meal), while most all Natural Marketing Programs will not allow feeding of animal proteins.  The subject of this article is not to differentiate between “natural” cattle and “all-natural” supplements, but to look at the efficacy of an all-natural supplement versus a supplement containing some NPN.