Soybean meal, soyabean meal, soya bean meal, sojabean meal, Manchurian meal

Scientific Name: Glycine max

Description

Soybean is the oilseed crop that is produced in the largest amounts in the world and is an important staple food for the Orient. This crop orginated in the Far East and is now produced in many parts of the world. Soybean are annual legumes and grow well in areas where corn can be produced, but cultivars have been developed that will grow in a wide range of conditions. It is primarily produced to be used as food or as a source of edible oil for human consumption. The oil can be removed by using either a solvent extraction method or by mechanically pressing the soybeans (expeller). Solvent extraction using hexane is the most common method used, because it is the most efficient method for extracting the oil and extracts a higher proportion of the oil. After the oil has been extracted out of the soybeans the residual meal is used as a supplemental protein source for feeding livestock. Soybean meal is an excellent feed for livestock it is very palatable, highly digestible and contains a high amount of digestible energy. The majority of the soybean meal is fed to poultry and swine with an increasing amount of specially processed soybeans being fed to dairy cattle. It is one of the most consistent feed ingredients available. The CP content of the soybean meal ranges from 41 to 50 % (dry matter basis) depending upon the amount of hull that is removed and processing method that is being used. The 41 % CP soybean meal is produced by expeller or hydraulically pressing soybeans that have not had the hulls removed (undecorticated). The 44 % CP soybean meal is produced by solvent extracting soybeans without removing the hulls. The 50 % CP would have the hulls removed prior to having the oil extracted using the solvent like hexane. There are several anti-nutritional factors associated with soybean meal, such as, trypsin inhibitors, saponins, phytoestrogens, glucinins, goitrogens, lectins, mineral binding substances and several additonal factors (CRC, 1983)(AGRIS 89-064508); (Liener, 1994)(AGRIS 95-124770). 

In order for the nutritional value of soybean meal to be maximized these anti-nutritional factors need to be inactivated or minimized. When these anti-nutritional factors are only partially inactivated, then there will be a corresponding depression in nutrient utilization. Trypsin inhibitors interfer with the enzymes trypsin and chymotrypsin. Trypsin and chymotrypsin are secreted into the small intestine by the pancreas and aids in the digestion of dietary proteins that have been consumed by an animal. The trypsin inhibitors bind to enzymes and causes trypsin and chymotrypsin to become non-function and therefore protein digestion is impaired (Liener, 1994)(AGRIS 95-124770); (Caine, et al, 1998)(AGRIS 1999-012575). When these inhibitors are present the animal will try to compensate by enlarging their pancreas in order to produce more enzymes. The trypsin inhibitors have the greatest effect on monogastric animals, such as, poultry and swine. It has a lesser affect on ruminant animals, because of the transformation that occurs in the rumen. The trypsin inhibitor is easily inactivated by heating the soybeans prior to feeding them. Urease is another anti-nutritional factor that is present in soybeans. Urease is an enzyme that converts urea to ammonia. When unprocessed soybeans are mixed with urea, then ammonia will be release, which is something that you don’t want to have occur in a mixed feed. The urease in soybeans is also easily inactived by heating. Soybean meal can be easily tested for its urease activity, which can be used as an indicator to determine if the soybeans have received the required minimum amount of heating during its processing. Tasting the soybean meal can also be used to determine if it has been adequately heated when it was processed. If it has a light brownish color and has a nut-like taste, then is has been properly processed and is safe to be fed to poultry and swine. Under-processed soybeans will have a “beany”raw taste and should only be fed to ruminant animals. Several other anti-nutritional factors have been found to be associated with soybeans. Phytoestrogens have been shown to cause infertility problems in sheep and cattle (Adams, 1995)(AGRIS 96-020483). Glucinins can cause allergenic reactions. Lectins will interfere with absorption of nutrients in the small intestine by animals (Liener, 1994) (AGRIS 95-124770). Phytic acid binds phosphorus and zinc and cause them to be unavailable to the animal.

Caution:  

Antiquality factors need to be inactivated in order to maximize performance. Many of these antiquality factors can be inactived by heating.

Source: 

By-product of soybean oil production

Feeding Experiments: 

Poultry Large amounts of soybean meal is fed to poultry. Methionine was found to be the first limiting amino acid with threonine, valine and lysine being also marginal when soybean meal was the only protein source being fed to poultry. Both under- and over-processing of soybean meal has been shown to depress average daily gains in broilers (Perilia, et al, 1997) (AGRIS 1998 066891). The addition of lysine to over-processed soybean meal (35 % protein solubility) was shown to improve performance back to what is considered to be normal for processed soybean meal would be in broiler chicks (Aburto, et al, 1998)(CAB 981416101). The bioavailability of choline in soybean meal was found to be 77 to 95 % in poultry (Emmert and Baker, 1997) (AGRIS 1998 085122). Much of the phosphorus and zinc are present in soybeans in the bound form, so various methods have been proposed to increase their availability. Microbial phytase was added to corn-soybean layer diets and egg production, egg weights and feed consumption were found to be significantly increased (Um and Paik, 1999) (CAB 991404256). Genetically modifying soybean by inserting a fungal phytate enzyme has been shown to be an effective way of increasing the availability of phosphorus in feeding applications with poultry and swine (Denbow, et al, 1998) (CAB 981412163). The presents of oligosaccharides (5 to 6%) in soybean meal were found to have a depressing effect on growth in poultry (Coon, et al, 1990) (CAB 1990 01302276)),(Leske, et al, 1991) (CAB 1991 06103768). Feeding whole soybean beans or soybean products that have only had a portion of the oil extracted to monogastric animals will increase the amount of unsaturated fatty acids that are being consumed, which causes the fat deposits to become soft (higher in unsaturated fatty acids) and undesirable in some markets. Normally full-fat soybean products need to be limited to 20 to 25 % in the diet to prevent this from happening.

Swine Soybean meal is an excellent supplemental protein source for use in the feeding of swine. Performance of swine fed soybean meal will be depressed if it has not been adequately processed to inactive the anti-quality factors. The presents of trypsin inhibitors decreases ileal digestibility of soybean protein and increased fecal losses of nitrogen in swine (Grala, et al., 1998) (AGRIS 1999 033007). Corn-soybean diets have been found to be limiting in specific amino acids. A low CP (13.5 %) corn-soybean based diets was found to perform similar to a 19.2 % CP corn soybean diet, when supplemented with lysine, tryptophan, threonine, methionine, isoleucine and valine, and fed to young pigs (Marvromichalis, et al., 1998) (CAB 991404506). Soybeans contain 5 to 6 % oligosaccharides which cause digestive problems in poultry, but doesn’t seem to be as much of a problem in swine. Removing oligosaccharides (raffinose and stachyose) from soybean meal by ethanol extraction prior to feeding was found not to have an effect on the growth of weanling pigs (O’Quinn, et al, 1997) (AGRIS 97-149488). A large portion of the phosphorus and zinc is complexed with phytic acid in soybeans and unavailable to the animal. Several types of phytase enzymes are available that can be mixed with the feed prior to feeding that will increase the amount of available phosphorus. The addition of a phytase enzyme and soaking of a corn-soybean meal ration prior to feeding to swine and poultry increased P absorption and decreased fecal P excretion (Liu, et al, 1997) (AGRIS 97162828), (Yi, et al, 1996) (AGRIS 97-022114),(Kornegay and Quan, 1996) (CAB 961410600), (Denbow, et al, 1995) (CAB 961401750). Soybeans contain unsaturated fatty acids that when consumed by swine will be deposited in the adipose tissue and their backfat will become increasingly soft as the amount of soy oil consumption increases. If enough soybean oil is fed to swine the fat will become so soft that it will run off the carcass. When the amount of whole soybeans or an equivalent amount of soy oil exceeds 20 to 25 % of the diet, then softing of the backfat can become a problem. If after slaughter the carcasses are being cured, then the presents of unsaturated fats will cause off-flavors to develop in the finished products.

Dairy and Beef Cattle The CP of soybean meal is highly degradable in the rumen of ruminant animals and because of this large amounts have not been fed to dairy or beef cattle. In recent years various methods for heat processing soybeans to reduce rumen degradation of CP have been developed, so the amount of specially processed soybean products have increased. Now various heat treated fat extracted and full-fat soybean products are available for feeding dairy cattle. Full-fat roasted soybeans to be an excellent feed for lactating dairy cattle. Feeding of full-fat soybeans to dairy cattle has also been shown as a way of increasing the conjugated linoleic acid level in the milk (Dhiman, et al, 1999) (CAB 20000403793), which has been shown to be a compound that reduces cancer in humans. Soybean flour and isolated soy protein have been used as a partial replacement for milk proteins in the formulation of milk replacers for calves. Soybean protein has one of the best amino acid profile of any of the oilseed meals, but it is still limiting with respect to its' amino acids content. Methionine and lysine were found to be the 1st and 2nd limiting amino acids, respectively in 6 week old calves when corn-soybean starter diets were fed (Abe, et al, 1998) (AGRIS 1999-012572). Corn-soybean diets were found to be able to support normal growth rate of 0.4 to 1.3 kg/day in 3 month old Holstein calves (Able, et al, 1997) (AGRIS 1998-o41187).

Fish Soybean meal is being increasing used in diets for use in feeding fish. It is critical that the soybean meal received proper heat processing prior to being fed, but shouldn't be overheated when processed. Digestibility and utilization of the CP fraction was high when fed to fish. Apparent CP digestibility of soybean meal by trout, carp and red sea bream was 90-93 % (Yamamoto, et al, 1998) (CAB 991404136). Soybean meal-corn based diets fed to catfish were found to be limiting in methionine (Cai and Burtle, 1996) (AGRIS 96160438).

Feeding and Handling Characteristics: 

Processing is critical when utilization of nutrients contained in soybeans is trying to be maximized. Heat processing is required to inactivate many of the anti-nutritional factors, but excessive heating will reduce nutrient utilization of the nutrients contained in soybean meal. Several methods are used for achieving the proper heat processing of soybeans. In order to properly process soybeans the moisture content, temperature and length of processing time need to be precisely controlled. Soybeans can be roasted in a rotating drum to which heat is being applied. Another method is to pressure-cook the soybeans at 115oC for ten minutes or at atmospheric pressure for two hours. Excessive heating wastes energy and reduces the nutrient availability, especially when being fed to monogastric animals. In feeding applications with dairy cattle some advantage has been found in applying additional heat to the soybeans, so that the solubility of the protein faction is reduced. This causes the protein to by-pass the rumen and be digested in the abomasum and small intestine of the dairy cow. Testing the urease levels in soybean meal is a good indicator of if the soybeans have been properly heat processed, because urease is inactived at about the same temperature as the trypsin inhibitors. Urease values are normally around 2 in raw soybeans and 0.05 to 0.2 in properly processed soybean meal. It is important to assure that the moisture content of soybeans that are going to be stored is below 15 %. Often when soybeans are harvested their moisture content is above 15 % and they must be dried prior to being stored. It is best to store soybeans in their whole form. Because ground soybeans will deteriorate rapidly when stored, especially in hot humid climate. Soybean meal can range in CP from 41 to 50 % (dry matter basis), depending upon its hull and oil content. The hulls of soybeans can be used as a low quality roughage source for ruminant animals. Various other products can be prepared from soybeans. Soy flour is derived from soybean meal by screening it and collecting the fine powder, it is higher in CP and often used as a partial replacement of milk proteins in milk replacers. Soy protein concentrate is prepared from dehulled beans that have had the fat extracted, then extracted with water and is often used as extender in various food products. Normally the soy protein concentrate is normally to expensive to be used in feeding applications for animals.

Nutrient Characteristics: