SOYABEAN
Common names
#Soybean, #soya bean, #soya, #soy, #haba soya, #soja bean, #miracle bean [English]; #soja, soya [Spanish]; #soja, #pois chinois, #haricot oléagineux [French]; #soja, #feijão-soja, #feijão-chinês [Portuguese]; #sojaboon [Dutch]; #Sojabohne [German]; #kacang kedelai [Indonesian]; #kedele [Javanese]; #kacang soya [Malay]; #balatong [Tagalog]; #Đậu tương [Vietnamese]; #فول الصويا [Arabic]; #সয়াবিন [Bengali]; #大豆 [Chinese/Japanese]; #Σόγια [Greek]; #סויה [Hebrew]; #सोयाबीन [Hindi]; #ಸೋಯಾ ಅವರೆ [Kannada]; #대두 [Korean]; #സോയാബീൻസ് [Malayalam]; #सोयबीन [Marathi]; #भटमास [Nepali]; #سویا [Persian]; #Со́я культу́рная [Russian]; #சோயா அவரை [Tamil]; #సోయా చిక్కుడు [Telugu]; #ถั่วเหลือง [Thai]; #سویا پھلی [Urdu]
Related by products
Description
The soybean is an erect leguminous plant, up to 1 m high. A fast growing herbaceous annual, it is native to Asia but currently grown worldwide. Its tap-root can extend to 2 m deep in good soil conditions, with secondary roots exploring the upper 15-20 cm of the soil. Roots bear nodules resulting from Bradyrhizobium japonicum infection (in most cases). Leaves are trifoliate and leaflets are oval to lanceolate, mostly broad in commercial cultivars . The papilionaceous flowers are white, pink, purple or bluish, with a 5 to 7 mm long corolla . Fruits are two or three-seeded pods containing yellow, rounded seeds with a hilum colour ranging from yellow to black .
Soybean is primarily an oilseed containing about 20% oil. Soybean is the largest oilseed crop, with 231 million tons produced in 2008, the main producers being the United States, Brazil, Argentina and China (FAO, 2010). The extraction of oil results in a high-protein cake that can be further processed into a variety of products for feed and food uses. One of these products, soybean meal, is one of the major feed commodities and is the main protein source in many animal diets. Soybeans can also be used whole (full-fat soybeans). While soybean used to be grown primarily for its oil, the expansion of the crop is now driven by the demand for soybean meal and feed use accounted for about two-thirds of the value of soybeans in recent years (FAO, 2006).
Soybean is used as food in tropical Africa and Asia. Western countries are a new market for soya food (exotic foods, soybean milk, tofu…). It is useful to make flour, milk, tofu and tofu-like products. It may be roasted and eaten as a snack, or fermented to make tempeh, miso, yuba and soy sauce. Immature soya beans are also eaten as a vegetable, as well as bean sprouts.
Soybean leaves and stems can be grazed, ensiled or dried to make hay. The foliage is very palatable to cattle, has a high nutritive value and is highly digestible . Average world soybean yields are 2.25 t/ha while average African soybean yields are 0,5 t/ha .
Genetically modified soybeans are now widespread in the main producing countries, and occupied 65.8 million hectares in 2008, about 68% of the world soybean area . In 2009, 91% of the US soybean surfaces were planted with GM soybeans, mostly herbicide-tolerant varieties (UDSA-NASS, 2009). Most of the grown GM soybeans have herbicide-resistance traits, but GM varieties have been developed for other traits, including resistance to fungi and insects, tolerance to drought and salinity, and improved nutritional and/or health characteristics: high oleic content, high protein and amino acid (especially methionine), reduced stachyose and raffinose.
The major soybean products for feed use are soybean oil, soybean meal (the by-product of oil extraction) and whole soybeans (usually called "full-fat"), the latter being usually heat processed in order to destroy the antinutritional factors and improve their feed value. These products can be ground, pelleted, flaked or powdered.
Other products include soybean flour (powdered and screened soybean meal with a very low fibre content), soybean protein concentrates and isolates (that contain more or less pure protein), soybean solubles and molasses (resulting from the washing of soybean flour and soybean flakes), soybean mill feed (by-product of the fabrication of soybean flour), and soybean mill run (by-product of the fabrication of soybean meal).
Distribution
Soybean is native to Asia. It was domesticated in North China 3000 years ago, and is now produced in almost all continents between 53°N to 53°S, and from sea level up to an altitude of 2000 m. The main producing countries are the USA, Brazil, Argentina, China and India.
Optimal growth conditions are average day-temperatures around 30°C, 850 mm annual rainfall, and not less than 500 mm water during the growing season, and soil pH ranging from 5.5 to 7.5 with good drainage. Soya is sensitive to soil acidity and aluminium toxicity. It can withstand short periods of waterlogging and short droughts .
Environmental impact
N-fixing legume, soil improver
Soybean is an N-fixing legume. It can be used as green manure or as a rotation crop in combination with cotton, maize and sorghum. During the first 6-8 weeks after seedling, soya has to be weeded. After that period, its rapid growth can reduce weeds. In Africa, it is reported to reduce the parasitic weed Striga hermonthica which is very noxious to crops .
Loss of biodiversity
The intensive monoculture of soybean in Brazil and Argentina has a negative effect on habitats and biodiversity. Soil erosion increases with mechanical weeding, and intensive cultivation results in a severe mining of soil fertility. Soybean cultivation is also responsible for massive deforestation in Brazil, Argentina and Paraguay .
Genetically modified soybeans
The debate about the environmental impact of GM crops is complex and a full discussion of the issue is beyond the scope of this datasheet. The actual reduction in herbicide use due to the introduction of glyphosate-resistant soybeans is disputed. The decrease of 10% found by certain authors can be considered too modest (or linked to factors other than GM soybean), or significant enough because of the large areas cultivated with soybeans. Other authors consider that herbicide-tolerant soybeans can have indirect environmental benefits by encouraging farmers to use no-tillage or conservation tillage practices that reduce soil erosion and fuel use (Edwards et al., 2009). Spontaneous, pollen-mediated gene flow has been observed but is considered too limited to be an issue. However, gene flow by seed is highly probable. Transgen introgression into wild soybeans in China and Korea, while possible, is also considered too limited to be of real concern .
Nutritional aspects
Whole soybeans are extremely valuable feed ingredients. They are a source of protein (35-45% of DM), oil (16-25% of DM) and energy (gross energy 23-24 MJ/kg DM). They contain low amounts of fibre (NDF 13%, ADF 8% and less than 1.5% lignin in the DM). Also notable is the lysine content of soybean protein (5.7-6.7% of the protein). Soybean oil contains more than 60% of polyunsaturated fatty acids, mostly linoleic acid C18:2 (50-57%). There is a large variability in soybean composition due to varietal, geographic and environmental factors (Hammond et al., 2005).
Antinutritional factors
Soybean seeds contain several antinutritional factors. The most important ones are trypsin inhibitors, hemagglutinins, lectins and saponins. Soybean was indeed used to demonstrate the existence and the role of trypsin .
Trypsin inhibitors: raw soybeans contain trypsin inhibitors that bind with trypsin (a digestive enzyme) in the small intestine and form an inactive complex that prevents trypsin from degrading feed proteins . Trypsin inhibitors also induce pancreatic enlargement, increased trypsin secretion and, therefore, lower N retention, growth and feed conversion . Leaves and stems do not contain trypsin inhibitors and there is no problem in using soybeans as roughage or silage (Koivisto, 2006). Due to these antinutritional factors, raw soybeans are unable to support growth requirements in monogastrics. Ruminants are not as sensitive because trypsin inhibitors are deactivated and degraded in the rumen . However, trypsin inhibitors are heat labile and largely destroyed by heating (Rackis et al., 1986) so heat treatment is required before feeding soybean products to animals, particularly to monogastrics.
Lectins are glycoproteins that bind with intestinal villi and reduce nutrient uptake. Lectins are also heat-labile.
Saponins are glycosides that diminish uptake of other nutrients.
Others anti-nutritional factors: soybean may contain antivitamins, urease and plant sterols that may interfere with the absorption of carotenoids and vitamin E .
SOYABEAN MEAL
Common names
Soybean meal, soyabean meal, soya bean meal, soybean cake, soybean oil meal, soybean oil cake [English]; tourteau de soja [French]; Sojaschrot [German]; Bã đậu nành [Vietnamese]; 大豆粕 [Japanese]; Соевый жмых [Russian]
Description
Soybean meal is the most important protein source used to feed farm animals. It represents two-thirds of the total world output of protein feedstuffs, including all other major oil meals and fish meal (Oil World, 2015). Its feeding value is unsurpassed by any other plant protein source and it is the standard to which other protein sources are compared . While it has been an accepted part of livestock and poultry diets in the USA since the mid-1930s , soybean feed production took off in the mid-1970s and then accelerated in the early 1990s due to a growing demand from developing countries. The expansion of aquaculture and prohibitions on the feed use of slaughterhouse by-products have also fueled the demand for this high-quality source of protein (Steinfeld et al., 2006).
Soybean meal is the by-product of the extraction of soybean oil. Several processes exist, resulting in different products. Soybean meal is usually classified for marketing by its crude protein content. High-protein types are obtained from dehulled seeds and contain 47-49% protein and 3% crude fibre (as fed basis). Other types of soybean meal include the hulls or part of the hulls and contain less than 47% protein and more than 6% crude fibre. In solvent-extracted soybean meals, the oil content is typically lower than 2% while it exceeds 3% in mechanically-extracted meals .
Distribution
Soybean meal is available worldwide. In 2014, soybean meal production reached 243 million tons and accounted for 62.5% of oil meals (Soybean Meal Info Center, 2018). Main producers were China (76 MT), the USA (44 MT), Argentina (33 MT), Brazil (33 MT), and the EU-28 (12.5 MT). Main exporters were Argentina and Brazil (Oil World, 2015). The EU-28 was the most important importer of soybean meal (22 MT) followed by South-East Asian countries like Indonesia, Malaysia, Thailand and the Philippines (Oil World, 2015). In the EU-28, soybean meal represented 61% of the proteins used to feed livestock, 16% of compound feeds, and an amount of 24 MT. In the region, the demand for partially defatted soybean meal from labelled non-GMO soybean was reported to be about 10% of the total amount of imported soybean equivalent (3.4 MT). This demand also addresses the need for organic farming, or locally produced soybeans in 2020 in the EU .
Processes
There are 3 main processes to extract soybean oil:
The most common process consists in extracting oil from soybean flakes by solvent. In the USA, virtually all soybeans (99%) are solvent-extracted. This method is the most efficient and about 1.5% oil is left in the resulting soybean meal.
The second method consists in a mechanical extraction by a screw press (expeller). This method yields less oil and a soybean meal containing more than 5% residual oil.
The third method combines extruding and expelling of soybean flakes, and uses solvent for oil extraction .
Before extraction, the soybean seeds undergoes differents treatments aimed at increasing oil extraction and soybean meal quality .
Pre-extraction treatments
Cooking
Cooking the seeds has positive effects on: moisture conditioning of seeds and easing dehulling, oil viscosity reduction, increasing plasticity of seed, breaking of cell walls, protein clotting by denaturation, sterilization and deactivation of thermosensitive enzymes, and destruction of thermolabile antinutritional factors .
Crushing and flaking
Crushing and flaking operations promote solvent extraction step by changing the permeability of the soybean flakes .
Dehulling
Dehulling is a facultative process that separates the oil-rich kernel from hulls which represents 8% of the seed and are mainly fibrous containing limited amount of oil. Dehulling also removes antinutritional factors.
Removal of antinutritional factors and improvement of protein solubility
While conventional extraction of oil from soybeans seeds is effective in removing ANFs, this is not true for mechanical treatments that do not use high temperatures. Extruding prior to pressing may help solving this issue in expeller soybean meal as it removes as much ANFs as conventional solvent extraction .
Enzyme addition and fermentation
Enzyme addition and fermentation of soybean meal have been done in order to remove antinutritional factors like NSPs and antigenic proteins from soybean meal but these treatments resulted in inconsistent improvements of soybean meal nutritive value (energy and digestibility of aminoacids) in monogastric animals.
Fine grinding
Fine grinding (also described as "micronization") of soybean meal and of full-fat soybean have been reported to increase ileal digestibilities of amino acids of those products in broilers. The fine grinding of soybean meal result in higher amino acid digestibilities than those of full-fat soybeans .
Environmental impact
The high phytate content of soybean meal requires supplementation with inorganic sources of phosphorus in monogastric animals. Dietary P in excess of animal requirements is excreted into the environment and becomes an environmental pollutant .
The high digestibility of the amino acids of soybean meal in diets for monogastrics and the high content of lysine allow the formulation of diets that contain less total protein than with other protein sources and less excess nitrogen in the feed, thereby reducing nitrogen excretion into the biosphere.
Soybean meals are usually extracted with hexane, a solvent that is extremely flammable and non-biorenewable, poses health risks and is regulated as a hazardous air pollutant .
Nutritional attributes
A highly palatable feedstuff, soybean meal is characterised by a high protein content (from 43 to 53% as fed) and a low crude fibre content (less than 3% for the dehulled soybean meals). It has a very good amino acid balance and contains high amounts of lysine, tryptophane, threonine and isoleucine, which are often lacking in cereal grains. However, the concentration of cystine and methionine are suboptimal for monogastric animals, and methionine supplementation is necessary . Amino acid digestibility is also very high (more than 90% for lysine in pigs and poultry) .
Soybean meal contains oligosaccharides such as raffinose and stachyose that cannot be digested by monogastric animals, due to the lack of a specific endogenous alpha-galactosidase. Raffinose and stachyose can cause flatulence and diarrhoea that may increase the digesta passage rate, and decrease digestion and absorption of dietary nutrients. In poultry, these oligosaccharides have been shown to decrease nitrogen-corrected true metabolizable energy, fibre digestion, and transit time . Low-oligosaccharide soybean meals are now available.
About 60-70% of phosphorus in soybean meal is bound to phytic acid, which is nutritionally unavailable to monogastric animals and reduces the availability of P and other minerals . Supplementation with inorganic phosphorus is required, and the addition of phytase may alleviate the problem. Low-phytate soybeans are under development but their productivity is still low .
Soybean meal is a poor source of B vitamins and lack of B vitamin supplementation in soybean meal-based diets may cause reproductive and performance problems in sows, older pigs and hens .
SOYABEAN HULL
Common names
Soybean mill feed, soybean mill run, soybean hulls [English]; coques de soja [French]; casca de soja [Portuguese]
Description
Soybean hulls are a by-product of the extraction of oil from soybean seeds . After entering the oil mill, soybeans are screened to remove broken and damaged beans, and foreign material (Extension, 2008). The beans are then cracked, and their hulls, which mainly consist of the outer coats, are removed (see figure above). Hulls are fibrous materials with no place in human food, but are very valuable for ruminants . Soybean hulls are often reintroduced in the final oil meal in order to reduce its protein content, resulting in soybean meal types with a maximum protein + fat guarantee of 44 to 48%. However, this end use decreases when the demand for high protein soybean meal increases. Soybean hulls are thus available and very valuable feeds for on-farm feeding of cattle .
Soybean hulls are light, flaky, and bulky. They require special consideration when handling: closed feeders are necessary when soybean hulls are fed outside, since the wind tends to blow the hulls away. During transportation, closed and covered trailers are also required . Pelleting hulls is a way to reduce bulkiness and reduce transportation costs, even though many manufacturers prefer unpelleted hulls to prepare compound feed .
Distribution
Soybean hulls are available wherever soybeans are produced. It is estimated that soybean hulls represent about 5% of soybean weight . According to world production of soybean, which was 308 million tons in 2014, it can be estimated that the production of soybean hulls was about 15 million tons in that year (FAO, 2016). Only a part of the total production is used directly as feed, since hulls are reincorporated in soybean meal to comply with the intended protein content .
Processes
Sieving, heating and pelleting
Soybean hulls have to be heat-treated and milled to reduce their bulkiness and lower their urease activity . After cracking of soybeans, the hulls first pass through a sieve which separates fines and meats from the true hulls. The hulls are then toasted in order to destroy the urease enzyme . After heat treatment soybean hulls are referred to as soybean mill run, soybean flakes, or soybran flakes . Since soybean hulls have a very low density, they can be milled and pelleted to lower bulkiness. However, many feed manufacturers prefer using unpelleted soybean hulls to make their own pellet mixtures .
Nutritional attributes
The nutritional value of soybean hulls is quite good but also highly variable . The variability of soybean hulls is mainly due to the misclassification between well-cleaned soybean hulls and soybean mill feed or soybean mill run, two by-products that still contain particles of seed kernels, and are thus higher in protein and lower in fibre . As a result, products marketed as "soybean hulls" can have a relatively high protein content (9-18% DM), and be highly digestible . The fibre in soybean hulls is rapidly fermented and may contain substantial amounts of pectin. Soybean hulls have a high NDF (52-74% of DM), but because of their small particle size, the effective NDF is much lower (Boyles, 1999). Soybean hulls are sometimes considered an energy feed rather than a roughage .
SOYABEAN FORAGE
Common names
Soybean forage, forage soybean, soybean hay, soybean straw [English]; soja fourrager, foin de soja, paille de soja [French]; palha de soja, feno de soja [Portuguese]; forraje de soya, paja de soya, heno de soya [Spanish]
Description
Soybean (Glycine max. L.) is a major legume crop grown for its protein- and oil-rich seeds but it also makes valuable forage for grazing, silage and hay.
Morphology
Soybean is a fast growing herbaceous annual native to Asia that is currently grown worldwide. It is an erect leguminous plant, which grows up to a height of 1.3 m. Its taproot can extend to a depth of 2 m in good soil conditions, with secondary roots exploring the upper 15-20 cm of the soil. Roots bear nodules usually resulting from the presence of Bradyrhizobium japonicum. The leaves are trifoliate and the leaflets are oval to lanceolate, mostly broad in commercial cultivars. The flowers are papilionaceous and white, pink, purple or bluish in colour, with a 5 to 7 mm long corolla . The fruits consist of 2 or 3 pods containing yellow, rounded seeds with a hilum colour ranging from yellow to black . Soybean varieties bred for forage are late maturing and taller (90-130 cm high) than grain varieties . Forage soybean has indeterminate growth. It is stemmier and produces more biomass than grain varieties. Forage soybean has a delayed maturity which is favourable to fodder quality . Genetically modified forage soybean has been developed .
Utilisation
Like other forage legumes, soybean forage has many valuable traits as fodder. Soybean leaves and stems can be grazed, ensiled or dried to make hay. The foliage is very palatable to cattle, and has a high nutritive value and good digestibility (Koivisto, 2006). Soybean forage is much valued in wildlife management as it is also palatable to deers . In the USA, before 1935 soybean used to be grown mostly for fodder, but after this date its value as an oilseed and protein crop started to outweigh its value as forage. However, there is a resurgence of interest in soybean forage whenever the economic returns of soybean grain decrease, for instance after drought or frost . Nowadays, the most commonly used soybeans forage are grain harvest by-products. The stubble, which is the residue of the crop that remains on the fields after bean harvest, can be cut and chopped to feed dairy cows and heifers . Soybean straw, which is the residue of threshing of the beans, can be used as a source of roughage for cattle .
Distribution
Soybean is native to Asia. It was domesticated in northern China 3000 years ago and is now grown worldwide between 53°N and 53°S, and from sea level up to an altitude of 2000 m. The main producing countries are the USA, Brazil, Argentina, China and India. In the USA, soybean was initially introduced in the mid-1800s for forage production , with 63% of the soybean crop area being intended for forage in the 1930s. However, as it became more profitable to grow soybean for protein and oil, forage production declined rapidly, from 21% of the area grown in 1941 to only 10% in 1948 .
Optimal growing conditions are obtained when average day-temperatures are around 30°C, annual rainfall is 850 mm, and not less than 500 mm, and water is available during the growing season. Forage soybean thrives in well-drained soils with a pH ranging from 5.5 to 7.5. Soybean is sensitive to soil acidity and aluminium toxicity. Soybean intended for forage is particularly tolerant to drought .
Nutritional attributes
Soybean forage pasture and hay
Soybean forage is relatively rich in protein, which varies between 11% and up to more than 22% of the DM. Fibre content is also quite variable, with ADF content ranging from 20% to more than 45% of the DM. It is relatively poor in lignin (about 6% DM). The main factor influencing soybean forage quality is the maturity at harvest. Protein concentration decreases during flowering and increases during pod formation, while fibre concentration changes inversely. The stem and leaf proportion of the plant decreases as the pod and seed components increase. The lipid content of the mature forage can reach 10% of the DM due to the presence of oil in the seeds . As a result, soybean forage is at its most nutritive when the beans are allowed to ripen before the crop is grazed or made into hay . The type of cutivar is also important, since late maturing cultivars tend to produce greater forage yields but lower quality forage than early maturing cultivars when harvested at the same stage of development . For instance in Australia, the protein content varied from 21 to 23% for an early maturing cultivar between early pod and full-size bean stage, and from 13 to 15% for a late maturing cultivar during the same period . It has been recommended to mix varieties at different stages of maturity in the same pasture to secure a longer grazing period . Hay quality follows the same pattern but leaf and seed loss increases with cutting and curing after mid pod-fill .
Soybean straw
The nutritive value of soybean straw is relatively poor with a protein content ranging from 4 to 12% DM and very high fibre contents (NDF about 80% DM). However, like other legume straws, it is a better roughage than most cereal straws.