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Does Your Protein Source Measure Up?

Michael Thornton, MS Protein is one of the most expensive ingredients in feed supplementation; therefore, it is important for producers to have an understanding of protein utilization by their ruminant animals and an assurance that their nutritional advisor/supplier considers the subject. Not all protein sources are processed the same way in ruminant animals. Some proteins are degraded in the rumen and are made in to bacteria and the bacteria become the source of protein in the small intestine for the animal. However, some proteins pass through the rumen undigested and are primarily digested and absorbed by the lower digestive tract. When this occurs, the ruminant animal has more total protein available for metabolism as needed to meet nutritional demands. These proteins can be used efficiently and cost effectively to feed ruminant animals if production demand exceeds the rumen’s ability to meet the animals’ nutritional needs. Bypass proteins, also known as protected proteins or escape proteins, are the proteins that escape degradation in the rumen and pass on to the abomasum and small intestine for digestion and absorption. The term “bypass” is misleading because these proteins do reside in the rumen for a short period of time, so they are more commonly and accurately referred to as “escaped proteins”. In certain situations there is a benefit in providing ruminant animals with bypass proteins, and AC Nutrition considers the balance of these proteins in our supplementation programs. The majority of protein for ruminant animals is protein made by microbes in the rumen, but bypass protein in supplemental feeds provides a method to change the type and increase in the amount of protein available for use by the animal. Rumen microbes degrade protein into smaller components such as amino acids and ammonia. These components are then used by the microbes in the rumen to produce microbial protein that is then passed into the small intestine for digestion and absorption. Although microbial protein is a beneficial source of protein, research has shown that in certain production situations protein produced by ruminal synthesis does not supply an adequate amount of amino acids needed for milk production and growth by ruminant animals. In these cases, bypass proteins can be supplemented to provide the protein needed to bridge the gap between the protein needed by ruminant animals and the amount of microbial protein produced by rumen synthesis. The key focus of protein supplementation is increased nutrition at a lower cost. This is accomplished by maximizing the intake of less expensive non-protein diet-dependent nitrogen used as a source of ammonia for rumen synthesis, optimizing the intake of natural proteins highly degradable in the rumen, and the bypassing of proteins from the rumen to the lower digestive tract if more total protein is needed. During times of growth and lactation, protein requirements significantly increase. In these cases, some ruminant animals may not be capable of producing enough total protein or some essential amino acids needed to meet their nutritional needs. Either an increase in the amount of protein fed is required, or a more efficient protein is needed to bypass degradation in the rumen, preserving digestion and absorption in the small intestine. Proteins sources have different bypass rates. Urea is a nitrogen source with no bypass value. Soybean meal has a bypass rate of 20%-40%. Proteins with medium bypass rates (40%-60%) include cottonseed meal, dehydrated alfalfa, corn grain, and brewers dried grains. Proteins with high bypass rates (60% +) include corn gluten meal and distillers dried grains. Many of the proteins with higher bypass rates, specifically corn gluten meal and distillers dried grains, are provided in various AC Nutrition supplementation programs, allowing optimal cost efficiency and nutritional value in protein supplementation.
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