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Effective supplementation brings together biology, economics on the ranch

by Wyoming Livestock Roundup

Supplementation is about providing cattle with the necessary nutrients to provide for growth and production, but South Dakota State University Ruminant Nutritionist Ken Olson adds that it is also important for producers to make sure they are getting the biggest benefit for their expenditures.

“There are two aspects we need to think about with supplementation,” Olson says. “First is the biology of the cow’s production, and the other aspect is the buck itself in terms of the economics of pricing potential supplements.”

He adds, “Both of these are really important to maximizing the value of our supplementation program.”

Biology of supplements

“We don’t need to supplement the cows in a green grass pasture situation,” Olson says. “We are talking about supplementing cattle on dormant, fully mature forage.”

Cows grazing dormant, mature forages during the winter months may not receive the nutrition they need. These forages are frequently very low quality.

“When we are talking about low-quality forages, the age old rule is that a forage with seven percent crude protein content or lower is what we are talking about,” he explains. “All dormant forages are not created equal.”

“When we talk about an average of seven percent crude protein in low-quality forages, that creates the first deficiency we need to talk about today,” Olson adds.

When plants are preparing for winter, they store many of their soluble nutrients in the roots to be saved for the upcoming years, leaving primarily fiber in the above-ground portions of the plant.


“Ruminants can digest fiber and use that as their primary energy source,” Olson says, “but we have to make sure the cow has the capacity to digest the fiber and use it.”

When referencing the capacity of the cow, Olson explains that a cow will eat forages, which move through the esophagus into the reticulum – the first compartment of the four-chambered stomach. After passing through the reticulum, forages are digested in the rumen.

“The feed stays in the rumen until particles get small enough to fit through the omasal orphus, which is the opening into the third compartment of the stomach,” he says. “The feed stays in the rumen until she can get as much of the nutrients out of it as she can. Sometimes, as we’re going to learn with low-quality forages, that can take a long time.”

When the rumen of the cow is full, she stops eating until it empties and more capacity is available. Receptors in the stomach work similarly to a float valve in a tank.

“With low-quality forages, it takes longer for the rumen to empty, so the rate of digestion passage slows and the quality of digestion goes down,” Olson comments. “Digestibility gets cut nearly in half as we go from our best forages to our worst forages, and intake gets hurt.”

Research shows that nearly a three-fold decrease can be seen on the amount of forage consumed as a percentage of body weight, which means that the cow is gaining less and producing less as a result.

Choosing a supplement

After it is determined that a supplement is necessary, Olson explains that choosing a supplement is important.

“We know we are deficient of some nutrients,” he says. “”We need to provide additional nutrients, but we can’t afford enough supplement to meet all of those. We have to help the cow do a better job of getting more fiber, and we need to overcome the limitations of digestion and intake.”

One key method to help a cow’s digestive system is to help the microbes in her cut.

“When we are feeding a cow, we are feeding for two,” Olson says, “and I’m not talking about her calf. I’m talking about the ruminant microbes. We need to meet their requirements first if we have a ghost of a chance of meeting the cow’s requirements.”

The definition of a seven percent crude protein requirement feeds the microbes in the cow’s gut. As a result, protein above that is necessary to supply the cow’s needs.

Right feedstuffs

Supplements are classified based on their protein content. Protein supplements are high in protein while energy supplements are low in protein.

The ratio of protein to energy is also important, and Olson explains that protein is the first limiting nutrient in many situations.

“If we provide more protein, microbes can feed, digest it and use that to grow more microbes,” he explains. “If we can grow more microbes, the cow can digest more fiber and she can increase the rate that she digests quite dramatically.”

Interactions among feeds can affect the nutritional value of forages.

“We can increase nutritional value of a forage by adding protein in the form of supplement,” Olson adds. “We can also cause negative associative effects.”

For example, grains are more efficiently digested than fiber. A grain-based energy supplement can be detrimental.

“Grains are mostly starch, and when starch competes with fiber to be digested, starch wins the war every time,” Olson explains. “If we overcome the protein deficiency, we can’t grow more microbes.”

At the same time, microbes will preferentially digest starches, leaving more fiber in the gut and further slowing digestion.

“The interaction of the feed combination is important,” he summarizes. “When we add one feed in combination of another, we can press the quality out of one we hope to get more out of.”


When seeking supplements, Olson also noted that producers must consider the cost per pound of crude protein, as well as the cost of transportation. He also urged producers to ensure they aren’t paying for unnecessary water.

“We need to evaluate our supplements on a crude protein basis, and we need to get them on the same dry matter content,” Olson said. “There are a variety of feeds, and we have to calculate the price per ton of crude protein.”

For example, he explained that in all his calculations over 30 years as a nutritionist, cake with 30 percent crude protein is always cheaper on a crude protein basis than 20 percent range cake.

At the same time, he also adds that tubs tend to be more expensive than any other crude protein sources, but he cautions producers, “There are reasons that we may use tubs. Sometimes, there are other reasons that supplements can be valuable, such as for improved pasture distribution or cost of hauling.”

Olson spoke during the 2015 Range Beef Cow Symposium, held in mid-November in Loveland, Colo.

Saige Albert is managing editor of the Wyoming Livestock Roundup. Send comments on this article to

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