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Clearing up Confusion on Protein and Energy Supplements

By Adele Harty
 
Differentiating between protein and energy supplements is key to developing an effective cattle supplementation program, but it can be very confusing. With the multitude of feed options available, understanding types of feeds and nutrient requirements will help ensure cattle perform optimally.
 
All feeds contain energy and protein, but feeds are differentiated based on the amount of each nutrient in the feedstuff. Frequently, the biggest challenge is determining whether a protein or energy supplement is needed. The only way to know for sure is to sample feeds and send them to a commercial laboratory for a nutrient analysis. Once deficiencies are identified, supplemental feeds can be evaluated to determine which one will meet animal nutrient requirements with little or no modifications or addition of storage and handling equipment, at the most economic price.
 
As a general baseline, rumen microbes require a diet that contains a minimum of 7% crude protein. The rumen microbes utilize the nitrogen in the protein to grow, multiply, and digest the fiber components of the forage. This level of protein does not take into consideration the requirements of the cow herself. That being said, protein supplements are frequently necessary to improve forage digestibility by rumen microbes when cows are being fed low quality forage or grazing dormant pasture.
 
A protein supplement can be any feed that will increase the protein content of the basal diet. Examples of protein supplements include by-product feeds such as distiller’s grains and corn gluten feed. Other common protein sources are alfalfa hay, soybean meal, range cubes, molasses lick barrels, protein blocks and liquid protein supplements. The protein levels on these feeds can range from slightly less than 20% up to 48% for the soybean meal. Some of the commercial products, including molasses lick barrels, protein blocks and liquid protein supplements may contain a higher level of protein, but a portion of the protein is supplied by a non-protein-nitrogen source, such as urea or biuret. Read feed tags to determine the protein source in commercial feeds.
 
Energy supplements are characterized by low protein content, normally less than 20%. Traditional energy supplements typically consist of grains that are high in starch content such as corn, barley, and oats. The challenge with providing these energy supplements with a low quality forage diet, is that starch interferes with forage digestion in the rumen by changing the rumen pH and making it a more favorable environment for those microbes that are more efficient at starch digestion. This decrease in rumen pH results in a decreased number of microbes for forage digestion. Fortunately, there are other energy supplements available that decrease the potential for these negative associate effects. They are characterized as a high fiber energy source, many of which are by-product feeds such as soyhulls, wheat middlings, and sugar beet pulp. These high fiber supplements provide additional energy without changing the rumen environment.
 

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