| PUBLISHED BY SOYBEAN GROWERS FOR THE FEED INDUSTRY | JUNE 2008 | |
| INFOsource | Page 3 | |
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| A Classic Soybean Meal Report from the Past: |
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Soybean Meal - The "Gold Standard" by: Gary L. Cromwell Professor, Swine Nutrition University of Kentucky |
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| Soybean meal has long been considered the best source of supplemental protein in diets for swine. In fact, it is often referred to as the "gold standard" in that all other protein sources are generally compared to soybean meal. However, in spite of its many virtues, soybean meal is not perfect; it has some shortcomings. A considerable amount of new research is being directed toward solving some of the problems associated with the undesirable factors in soybean meal, and these will be discussed in this paper. The swine nutrition group at the University of Kentucky has participated in some of this research. But first, let's look at soybeans and soybean meal from a broad perspective. Soybean meal is by far the most widely used protein source in the USA and throughout the world. Soybean acreage accounts for about 26% of the crop land in the USA, similar to that devoted to corn (29%) and wheat (26%) production and considerably greater than the crop land devoted to cotton (5%), sunflower (1%), and other oilseed crops. On a global basis, soybean meal accounts for approximately 63% of all protein sources used in animal feeds followed by rapeseed (canola) meal (12%), cottonseed meal (8%), sunflower meal (6%), fish meal (4%), and peanut meal (4%). However, in the USA, soybean meal accounts for approximately 92% of the total oilseed meals fed to livestock and poultry. Approximately 53% of this soybean meal is used in poultry feeds followed by 27% in swine feeds, 14% in cattle feeds, and 6% in pet foods, fish feeds, and miscellaneous feeds. The popularity of soybean meal in swine and poultry feeds is largely due to its high concentration of protein (44 to 48%) and its excellent profile of highly digestible amino acids. Although not a perfect blend of amino acids (it tends to be low in methionine), soybean meal is a rich source of lysine, tryptophan, threonine, isoleucine, and valine -- the amino acids that are seriously deficient in corn, grain sorghum, and other cereal grains that are commonly fed to pigs and poultry. The exceptional quality of soy protein is evidenced by its high content of lysine, the first limiting amino acid for pigs. There is approximately 6.5% lysine in the protein of soybeans and soybean meal. Actually, the concentration of lysine in soy protein is not greatly different from that of pork muscle protein, which ranges from 6.5 to 7.0% lysine. Other oilseed meals have considerably less lysine in their protein. For example, the lysine percentage in canola meal protein is 5.8%, in cottonseed meal, 4.2%, in peanut meal, 3.4%, and in sunflower meal, 2.8%. Some of the protein sources of animal origin have higher concentrations of lysine in their protein (dried blood plasma, 8.8%; dried milk powder, 8.3%; dried blood meal, 8.4%; fish meal, 7.6%; dried whey, 7.4%), while others do not (meat meal, 5.7%; meat and bone meal, 4.9%; feather meal, 2.5%). The two major kinds of soybean meal available for use in the swine industry are regular 44% protein soybean meal and dehulled soybean meal (47-48% protein). Both types are "solvent-extracted" which means that solvents are used to extract the oil from the soybeans. The oil-extracted residue is then heated to drive off the solvent and the meal is carefully toasted to destroy the inhibitors (discussed later). Soybean hulls are either blended back with the meal to standardize the protein to 44%, or they are not added (resulting in dehulled soybean meal). Either type of soybean meal can be used in swine diets. Besides being higher in amino acids, dehulled soybean meal is also slightly lower in fiber and higher in energy. But it is also priced higher than regular 44% protein meal. Because the amino acids in both types of meal are in direct proportion to the crude protein content, one can compare the cost per unit of protein in the two types of meals and select the one that is the best buy. Anti-Nutritional Factors in Soybeans and Soybean Meal Most all of the oilseeds possess a certain amount of anti-nutritional factors, and soybeans are no exception. Several of these factors are known to cause depressed growth performance in swine. Some of these factors can be reduced or eliminated by various processing methods. Also some have been reduced or eliminated by breeding programs. |
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