Greg Lardy: Factors affecting cattle’s need for protein supplementation
November 26, 2010
This year, many ranchers in the Tri-State Livestock News coverage area grew excellent grass and stockpiled it for use as dormant forage for fall and winter grazing. If you are planning on using dormant forages – particularly native forages – this winter, protein supplementation will generally be required to maintain beef cow productivity, ensure healthy calves at birth and ensure cows return to estrous quickly following calving.
The need for supplementation depends on cow condition, cow nutrient requirements, previous forage and pasture management, and weather. You should also consider other management factors such as calving and weaning dates, which impact cow requirements. Dormant forages are typically low in protein, vitamin A and minerals such as phosphorus. Table 1 shows the seasonal changes in forage quality on native rangeland near Dickinson, ND. It shows that, by fall, forages fell below the nutrient requirement for gestating cows.
Forages such as alfalfa hay, oilseed meals such as sunflower meal, grain processing coproducts such as dried distillers grains, and a myriad of commercial products can all be used for supplements. The choice depends on cost, availability, pasture accessibility and factors which are important to certain producers such as the convenience of self-fed products.
Extension personnel and feed company nutritionists have access to data for your area. With their help, you can fine-tune your supplementation program and improve overall returns by knowing diet quality, intake and cow requirements, and then supplement with the right products at the right time.
The purpose of protein supplements is, first, to provide a nutrient source for the rumen microorganisms and, second, to provide nutrients for the cow. In order to provide the cow with energy, protein and other nutrients, the bacteria in the rumen need rumen degradable protein to efficiently ferment the fiber in dormant forages. Most oilseed meals and grain processing coproducts contain relatively high proportions of rumen degradable protein. In the case of distillers dried grains, however, about 60 percent of the crude protein is rumen undegradable or escape protein. Research indicates that it can still work well as a protein supplement for low quality forages because the cow is able to recycle nitrogen to the rumen in the form of urea.
This leads to a common question that comes up during discussions on protein supplementation – “Can urea be included in a protein supplement?” The answer is yes. I typically recommend that no more than 40 percent of the crude protein (CP) units in the supplement come from urea. For example, if you buy a 30 percent crude protein supplement, no more than 12 of those crude protein units should come from urea (30 percent CP times 40 percent urea = 12 CP units from urea).
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The logic behind this recommendation is that, while some species of ruminal bacteria can utilize urea as a sole source of protein, many require preformed amino acids and/or peptides from natural protein sources in order to thrive. Those that require amino acids or peptides also tend to be species that are very important in fermenting fiber. Consequently, you generally see improved performance with the inclusion of some natural protein in your supplemental protein package.
Research data from across the country indicate that protein supplements don’t need to be fed daily. In fact, several studies indicate they can be offered as infrequently as once a week and still achieve similar performance. The reason is that God has graced the cow with the ability to recycle this protein (actually she recycles the urea) to the rumen. This means fuel and labor savings for you. Many commercial self-fed products (cooked molasses blocks, self-fed liquids, salt limited supplements and others) can also cut down on supplement delivery costs. These self-fed products are particularly useful in situations where pastures are a long distance from the ranch or farm and daily supplementation with conventional supplements may be cost prohibitive. In addition, these self-fed products can be used to improve pasture utilization by drawing cattle into areas where terrain or other limitations might otherwise reduce utilization.
In summary, protein supplements may be needed on many of the pastures your cows are grazing this fall and winter. Don’t wait until the cows have lost condition to evaluate your supplementation program. Evaluate the situation now, determine the most cost effective approach and strategically plan your supplementation program. Consult your local Extension personnel or feed company nutritionist for more information in order to make informed and cost effective protein supplementation decisions.