Beef Cow Protein Supplementation: Is there a Right Choice?

CRYSTALYX® Brand Supplements


“Which protein product do I need?” This question comes up with some frequency when speaking with producers about available protein options and since we are entering the primary protein season of the year, it might be helpful to share a short refresher about the differences between livestock diet protein sources.


A protein tutorial  

Natural or “true” protein refers to the nutrient coming from either plant sources (soybean, cottonseed and canola meal are all protein-rich byproduct examples) or animal sources (feather meal, blood meal and milk, to name a few) that are approved for ruminant feeding. You may be wondering why this is. Feather meal originates from avian species and avoids animal products of mammalian origin. While non-protein nitrogen (NPN) is not a true protein but rather a source of nitrogen, it is used by rumen microbes to manufacture their own natural protein. Similarly, the same urea applied as a fertilizer to plants is used to manufacture plant protein. This rumen microbial protein is a major source of daily nutrition to the animal, often amounting to 50 percent or more of the daily protein requirement for cattle as they digest this rich protein source. The key is that, for NPN to be utilized, the rumen needs to be functioning. However, one should keep in mind that young calves cannot utilize urea or NPN due to their lack of rumen microbes. They will develop the ability to convert NPN into microbial protein as the rumen develops from eating grains and forages.

Plant and animal proteins tend to be broken down relatively slowly, over several hours, by rumen microbes and in the small intestine. On the other hand, NPN is utilized quickly by microbes, so it is important not to overwhelm these microbial bugs with too much at one time. Just like providing fuel for a motor, too much can cause the engine to stall out, so it needs to be properly metered. When putting efficient diets together for cattle, we try to focus on matching protein and energy sources that break down at a similar rate.

Making the right choice

Let’s focus on the initial question: when should you choose all-natural plant and animal sources, and when would NPN be of benefit? The answer is it depends. When the focus is on very young calves, natural proteins will be utilized best, since the rumen is not yet fully developed. Most of their diet will be milk, plus whatever comes from grain, grass or hay. Urea is very soluble, meaning it dissolves into rumen solution quickly and is converted to ammonia, which is readily available for rumen microbes to utilize, as mentioned previously. Diets with medium- to low-quality hay, cornstalks or other dried forages will generally be fairly low in soluble protein, so the rumen microbes of older cattle can benefit from some urea in the diet. Matching this with a rapidly available energy source such as molasses helps to accelerate microbial growth, which promotes efficient forage fiber digestion. Conversely, NPN will generally not benefit the diet in the spring when grass is rapidly growing, as wet grass contains relatively high levels of soluble protein already, so the self-fed protein supplement advantage will come mostly from sugars in the molasses, plus mineral and vitamin fortification.

When the balance of ammonia builds up in excess of microbial protein growth, it will diffuse from the rumen into the blood. The liver will then pick up the excess ammonia, convert it back into urea and pass it back into the blood, where the kidneys will filter it out and eventually excrete it into urine. This helps keep the body’s ammonia levels in check. An entirely different article could be written describing how, when this system is overwhelmed with ammonia in the blood, urea toxicity can come into play. Thankfully, molasses is a very soluble carbohydrate source and stimulates microbial growth and the utilization of ammonia to remove any risk of urea toxicity. The tightly controlled consumption of a self-fed protein supplement can further protect cattle from issues related to over-consumption and eliminate the concern for urea toxicity. 

Of course, as with any diet, balance is key. Rapidly available nitrogen plus rapidly available sugars helps the growth of fiber-digesting rumen microbes. Some less rapidly available proteins/nitrogen are also necessary and are provided by natural protein sources that match with carbohydrate (energy) sources from the forage and grain portions of the diet. Complete the diet with the necessary minerals and vitamins and voilà: you get a healthy, high-producing herd of cattle. 

Self-fed protein supplements for the win

There you have it. This is how self-fed protein supplements help to complete a ruminant diet for cattle. As we approach colder weather and the inclusion of hay, cornstalks or other low-protein dried forages in the diet, a blend of natural protein and urea can be beneficial for older cattle. Testing your forage to know the protein and energy content is a highly recommended practice for achieving proper balance for the herd.

Work with your local CRYSTALYX® Brand Supplements dealer to help match the right self-fed supplement product(s) with the available feeds at your farm. Balancing the diet to let the rumen function in an optimal and safe manner will reduce the risk of over- and under-feeding protein.