Description and recommendations
Wheat bran, fine wheat bran, coarse wheat bran, coarse wheat feed
Wheat bran, a by-product of the dry milling of common wheat (Triticum aestivum L.) into flour, is one of the major agro-industrial by-products used in animal feeding. It consists of the outer layers (cuticle, pericarp and seedcoat) combined with small amounts of starchy endosperm of the wheat kernel. Other wheat processing industries that include a bran removal step may also produce wheat bran as a separate by-product: pasta and semolina production from durum wheat (Triticum durum Desf.), starch production and ethanol production.
It is important to note that wheat bran is not a product with a universally accepted definition and clear boundaries. Though national regulations may contain mandatory requirements on bran composition, ingredients sold under that name encompass a wide range of wheat by-products. Milling yields variable proportions of flour, depending on the quality of the final product. The extraction rate (flour:grain ratio) goes from 100% for a wholemeal flour to less than 70 % for pastry flour. Typical extraction rates range from 75 % to 80 %, resulting in 20 to 25 % wheat offals (Kent et al., 1994). Wheat bran represents roughly 50 % of wheat offals and about 10 to 19% of the kernel, depending on the variety and milling process (Ash, 1992; WMC, 2008; Prikhodko et al., 2009; Hassan et al., 2008). In the industrial milling process, after a cleaning step that removes grain impurities, the grains are tempered (soaked to toughen the outer layers and mellow the starchy endosperm in order to facilitate their separation) and then subjected to a series of grinding operations that produce finer and finer flour particles. The first grinding steps steps yields coarse particles of broken wheat and bran and the later steps produce other by-products (WMC, 2008). Milling by-products are traditionally named after their quality (fineness, colour...) and/or the stage of the process at which their arose, with considerable variations between languages, countries, regions, milling processes and even mills. In industrial countries, these products used to be sold separately (coarse bran, fine bran, middlings, second clear, thirds etc.) but are now mixed together in variable proportions (McDonald et al., 2002).
Consequently, wheat milling offals form a continuum of products with a decreasing fibre:starch ratio, from the fibrous coarse brans produced by the first grinding steps to starchy feed-grade flours. Wheat brans sold for animal feeding are typically mixtures of true coarse brans and finer products from the later grinding stages. In rural and traditional milling, flour is directly separated from bran in a one-step milling and screening. This type of bran has a higher starch content and a higher nutritive value (Piccioni, 1965). In Ethiopia, farmers prefers high-density bran since weight indicates that bran contains more flour and thus higher energy (Gebremedhin et al., 2009). The situation is made even more complex by the existence of wheat brans from other wheat species (durum) and wheat processing industries.
Wheat bran is suitable for livestock feeding and very palatable to most classes of animals (Fuller, 2004; Piccioni, 1965). Wheat bran is a bulky feed that can be used to lighten dense, heavy feed mixtures. It can be readily incorporated into mashes. Good bran should have a fair coating of flour and be in the form of large, dry and non-adherent flakes. It is sold in raw form or pelleted (Göhl, 1982).
Wheat bran is exported worldwide and a major feed commodity. However, worldwide production figures are difficult to assess. Wheat production for human consumption (total supply minus wheat produced for animal feeding, seed or wasted) can be estimated at 456 million tons in 2007. When calculated using a bran production rate of 10-19 % (see above), worldwide wheat bran production is comprised between 45 and 90 million tons. The main producers should be the main users of milled wheat: China, India, United States of America, Russian Federation, Pakistan, Turkey and France (about 75 % of the production) (FAO, 2011).
Wheat bran contains pentosans which are thought to have anti-nutritive activities in poultry and result in and depressed nutrient utilization and poor growth (Choct et al., 1992).
Wheat bran has a high phytase activiy, which is beneficial to phosphorus availability in pig and poultry diets. However, this phytase activity may considerably reduced when wheat bran is processed into pellets because heat treatments destroy phytase (Cavalcanti et al., 2004).
Lipase hydrolytic rancidity
Wheat bran contains a very heat-stable lipase which causes hydrolytic rancidity and is all the more active that the bran is finely ground (Allen et al., 1994). However, wheat bran contains low amounts of fat and no health problems due to rancidy has been reported in livestock.
Nutritional Secondary Hyperparathyroidism
Large amounts of bran can induce calcium deficiency in horses, known as Nutritional Secondary Hyperparathyroidism also known as "big head disease", "bran disease" or "Millers Disease" in horses because milling companies often fed their horses rations containing high amounts of bran (Kohnke et al., 1999). Growing bone is frequently rachitic and brittle and fractures may be common and heal poorly. Swelling and softening of the facial bones and alternating limb lameness are frequently reported (Kahn, 2005).
Proteins, minerals, oil and fibre are mainly found in the outer layers of the grain and wheat bran is richer in these nutrients than the whole grain. Wheat bran is relatively rich in protein (14-19 % DM, sometimes higher) and minerals (4-7 % DM), notably calcium (0.07-0.2 % DM) and phosphorus (0.9-1.3 % DM). Its oil content (3-5 % DM) is higher than that of the whole grain. The fibre and starch contents are inversely correlated and extremely variable, as they depend on the relative amounts of envelopes, endosperm and other fractions mixed together. Still, a product marketed as bran should contain relatively high amounts of fibre: crude fibre 7-14 DM, NDF 35-54 % DM, ADF 9-16 % DM and low amounts of ADL 2-4 % DM. Wheat bran should also contain about 15-30 % DM of starch (Feedipedia, 2011). Fibre is the main constraint for the utilization of wheat bran in animal nutrition, particularly in monogastrics. For that reason, the energy values of wheat bran (DE, ME, NE) are always lower than those of the whole grain, in all animal species.
Tables of chemical composition and nutritional value
When available, wheat bran is often a component of concentrate ruminant diets, due to its content of important nutrients: protein, minerals, fibre and starch. Maximum recommended inclusion rates are 10 % in calves, 20 % in dairy cows, 25 % in beef cattle, 5 % in lambs and 20 % in ewes (Ewing, 1997). It has a slightly laxative effect, partly because the bran fibre is only modestly digested (Göhl, 1982).
Like maize grain and soybean meal, wheat bran is such an important staple of ruminants diets that most trials involving wheat bran are about replacing it with local ingredients. The following paragraphs are recent examples of such utilizations.
In Bangladesh, a comparison of fishmeal and wheat bran diets for local lactating cows, it was concluded that the use of wheat bran resulted in slightly higher net returns over feed costs from selling milk due to the lower cost of the wheat bran diet (Khan et al., 1992). In Pakistan, a comparison of maize bran, wheat bran and rice bran for milk production of Holstein Friesian cattle showed that wheat bran allowed lower performance than maize bran, but higher performance than rice bran (Tahir et al., 2002). In India, wheat bran supplementing crossbreed dry cows on a straw diet supplemented gave superior results than supplementation with deoiled rice bran (Singh et al., 2000).
In the USA, the supplementation of beef cows and steers consuming low-quality, tallgrass-prairie forage with wheat offalls - bran or second clear (a high-starch) - and soybean meal showed that the nature of the milling by-product did not affect performance or intake and digestion of low-quality forage, as the sufficient degradable intake protein was able to mask any negative effects exerted by increasing levels of starch (Farmer et al., 2001). The supplementation of steers grazing endophyte-free fescue pasture with wheat bran at 0.48% of live weight increased live weight gain, but less than the supplementation with cracked maize (Hess et al., 1996). In India, the supplementation of crossbreed cattle bulls fed chopped green sugarcane tops with a concentrate mixture of wheat bran (50%) and lentil chuni (by-product of lentil processing) (50%) resulted in better performance with respect to intake, digestibility of nutrients and growth than when the supplement contained only wheat bran or only lentil chuni. This was explained by better rumen fermentation with the wheat bran+lentil chuni supplement (Gendley et al., 2002; Gendley et al., 2009).
In India, in growing lambs fed wheat straw as sole forage, replacement of maize grain with the cheaper wheat bran reduced the cost of concentrate mixture as well as feed cost per unit of live weight gain. Feed conversion efficiency was not affected and it is concluded that half of the maize grain can be safely and economically replaced with wheat bran in the concentrate mixture of growing lambs without any adverse effect on their performance, supporting an 85-90 g daily gain (Dhakad et al., 2002). In adult sheep, barley grain supplementation could be replaced with wheat bran up to 50% in the diet (Singh et al., 1999). In Ethiopia, no effect of supplement composition was detected on body weight gain in Farta sheep fed hay with sole or mixtures of niger seed meal (Guizotia abyssinica) and wheat bran (Fentie et al., 2008).
In India, wheat bran supplementation improved the utilization of various nutrients in goats fed on mixed straw as the roughage source (Maity et al., 1999). In Brazil, weight gain and food conversion were not affected by the inclusion of rough wheat bran in the diet instead of maize in the diets of growing goats and it was concluded that up to 14 % wheat bran could be included, as the diet contained less than 50 % NDF (Dias et al., 2010).
Wheat bran is a common ingredient in pig diets. It is usually palatable and can be fed to all classes of pigs with few problems. The main constraint is its high fiber content, which reduces its energy density: the net energy content of wheat bran represents 60 and 65 % of the NE value of wheat for growing pigs and adult sows, respectively (Noblet et al., 2002). These energy values can be accurately estimated from measured chemical parameters (EvaPig, 2010).
Pigs fed diets containing wheat bran tend to increase their feed consumption at a rate such that energy intake remains constant (Levasseur et al., 1998). This compensatory effect depends on the inclusion rate of wheat bran and on the duration of period of adaptation to the bulky diet (Kyriazakis et al., 1995). The bulkiness of wheat bran limits its use in diets formulated for physiological stages where dietary energy content must be maximized (starter and grower pigs, lactating sows) and/or for housing conditions where appetite is limited by environmental factors (poor sanitary status, warm climate). In contrast, wheat bran can be used as an energy diluent during gestation in order to reduce hunger and improve welfare (Ramonet et al., 1999), health status (Meunier-Salaün et al., 2001) and reproductive performance (Matte et al., 1994). Gestation diets can contain up to 30 % of wheat bran. The use of wheat bran-rich diets around parturition is sometimes recommended to prevent sow constipation and metritis-mastitis-agalaxia syndrome (Etienne, 1987).
Data about the inclusion of high rates of wheat bran in lactation and grower/finisher diets are scarce. Wheat bran used at 48.5% in lactation diets did not impact the performance of low productivity sows (Schoenherr et al., 1989). This may not be the case in highly productive lactating sows and lower inclusion levels are then recommended in most lactation diets. In tropical conditions, sows performance during lactation were maintained when 36 % of wheat bran were included in the diet (Renaudeau et al., 2003). Increasing wheat bran inclusion from 0 to 20 % did not significantly influence growth rate of growing pigs between 20 and 90 kg but increased the feed conversion ratio (Newton et al., 1983). When diet with wheat bran is formulated in order to maintain the same NE content (with fat addition), both growth rate and feed conversion ratio are similar to a diet without wheat bran (Levasseur et al., 1998). The finisher diet can contain up to 30 % wheat bran without any negative effect on performance (Hines, 1980).
The nutritive values of wheat bran for poultry found in tables and publications are highly variable, due to the wide range of products found under this name. However, whatever the origin, protein, starch and lipid contents are relatively low while the fibre content is high. As a consequence the ME value is low and can be estimated by a fibre measurement such as the crude fiber (Boudouma, 2010a). When diets are calculated by least-cost formulation, inclusion rates of wheat bran are generally low. In countries where this cereal by-product is abundant and inexpensive, low energy pelleted diets containing large amounts of wheat bran might be used. Large amounts of wheat bran can be used in molt diets for layers (Soe et al., 2009).
When diets are presented as mash, high inclusion rates (> 13 %) of wheat bran tend to reduce feed intake in broilers (Boudouma, 2010b). Pelleting diets may overcome the detrimental effects of low density diets containing wheat bran. Laying hens fed diluted diets in which nutrient density was reduced by inclusion of 45 % wheat bran adjusted their feed intake only when the diets were pelleted while hens fed the mash diet ate less and produced lighter eggs (Vilarino et al., 1996).
Wheat bran is a natural source of betaine which is known to have positive effects on osmoregulation, carcass fat reduction and on choline and methionine sparing in poultry (Kidd et al., 1997).
For rabbits, wheat bran is an valuable source of energy, digestible fibre and protein. It is very frequently introduced in commercial diets (Lebas et al., 1984b; de Blas et al., 2010) and in reference diets in animal trials (Lebas et al., 2009). The inclusion level in experimental diets is frequently 45-50 % or more, up to 64-65 %, in studies on wheat bran itself or on ingredients replacing part of wheat bran in the control diet (Aduku et al., 1986; Berchiche et al., 2000; Blas et al., 2000a; Blas et al., 2000b; Fotso et al., 2000; Gidenne, 1987; Gu et al., 2004; Lakabi-Ioualitene et al., 2008; Lounaouci-Ouyed et al., 2011; Lounaouci-Ouyed et al., 2012; Parigi-Bini et al., 1984; Singh et al., 1997; Villamide et al., 1989). If necessary, wheat bran may represent more than 98 % of the diet, without problem (Robinson et al., 1986). In commercial feeds the introduction level is more moderate and is generally in the 15-35 % range (de Blas et al., 2010). In the experimental diets presented during the 2008 World Rabbit Congress, the average inclusion level was 19.1 % (Lebas et al., 2009).
Wheat bran can be used in growing rabbit feeds as well as in breeding does feeds, provided that the nutritional requirements are met (Hoffmann et al., 1993; Muir et al., 1995; Salma et al., 2002). Very high inclusion rates may be problematic due the large variability in the starch content of wheat bran, as the diet starch content must be limited for rabbit kits around weaning (Gidenne et al., 2010).
The crude fibre and correlatively the ADF level of wheat bran is lower than the minimum recommended for rabbits (de Blas et al., 2010) but the hemicellulose content is more important (about one third of the product) and this highly digestible fraction (72 % according to Gidenne, 1987) plays an important role in preventing digestive diseases (Gidenne et al., 2010).
Wheat bran is also an excellent source of phosphorus. The fact the most of bran phoshorus is phytate-bound has no consequence on the digestive utilisation of phosporus in rabbits since their digestive tract has an important bacterial phytate-degrading activity (Nelson et al., 1985; Furlan et al., 1994). However, in breeding does, the high phosphorus content of wheat bran may limit its use to moderate inclusion rates, as phosphorus becomes relatively toxic when more than 0.75 % is present in the diet (Lebas et al., 1984a; Lebas et al., 1990)
A very fine grinding of wheat bran (1 % particle remaining on the 1 mm sieve vs 36% for the whole wheat bran) fails to modify protein or crude fibre digestibility and improves only slightly (+ 3 %) dry matter and energy utilization (Robinson et al., 1986).
Durum wheat bran
Durum wheat bran is more rarely used that bran from the bread flour industry, but large amounts are produced in countries with semolina or pasta industries. Experiments conducted in Algeria show that durum wheat bran may be used in rabbit feeding with the same limitations, if any, than common wheat bran (Berchiche et al., 2000; Kadi et al., 2004; Lakabi-Ioualitene et al., 2008).
Horses and donkeys
Wheat bran can be given to horses up to 2 kg per day (Göhl, 1982). Horses find it palatable and enjoy eating feeds containing up to 10 % bran (DM basis). Though it has long been popular as a laxative feed for stabled horses, this laxative effect is not significant as horses consume other sources of fibre. High inclusion rates of bran can induce calcium deficiency (See Caution above). Calcium, zinc and iron supplements should not be mixed into large amounts of bran, as they may become bound to the phytate in the small intestine, which will lower their absorption rate (Kohnke et al., 1999).
The high fibre content of wheat bran limits its use to herbivorous and omnivorous fish. General recommended rates are 2-5 % and wheat bran should preferably be extruded (Hertrampf et al., 2000). Wheat bran has been tested and used in numerous fish species and higher inclusion rates seem possible in certain cases.
Nile tilapia (Oreochromis niloticus)
The nutrient digestibility of wheat bran in Nile tilapia was found to be relatively high for protein (75-84 %) and amino acids (78-87 %) but very low for energy (37-39 %) and generally much lower than nutrient digestibilities of fish meal and other protein sources (Maina et al., 2002; Ribeiro et al., 2011; Sklan et al., 2004). Wheat bran is one of the main ingredients used by tilapia farmers in Subsaharan Africa (El-Sayed, 2013). In Kenya, with Nile tilapia fingerlings fed cereal brans (maize, wheat and rice) at 1.5 % body weight, growth obtained with the wheat bran treatment was intermediate between that allowed by maize bran (highest) and rice bran (lowest). However, wheat bran was more profitable (Liti et al., 2006).
Common carp (Cyprinus carpio L.)
Common carps fed wheat bran at 3 % body weight 3 times daily had better growth, feed conversion, DM in carcass, protein and energy retention than carps fed rice bran (extruded or not) but performance were lower than for carps fed biscuit wastes and wheat middlings (Shalaby et al., 1989). In carps fed a diet containing 48.5 % of test ingredient, protein digestibility was higher for wheat bran (81 %) than for sorghum grain but lower than for rye. Lipid digestibility was the highest for wheat bran (82 %) (Degani, 2006). A carp diet containing 10 % of wheat bran gave better peformance than when 20 % wheat bran was used (Rahman et al., 1989, cited by Hertrampf et al., 2000).
Other carp species
Wheat bran included at 30 % in the diets of fingerlings of 3 Indian carp species (Catla catla, Labeo rohita, Cirrhinus mrigala) was found to be a suitable ingredient, with relatively high digestibilities for protein (93 %) and energy (80 %). Carbohydrate digestibility was lower (68 %) and inferior to that of cooked maize but still higher than that of rice bran and rice polishings (Erfanullah et al., 1998). Labeo rohita carps fed diets containing up to 5 to 15 % wheat bran had a better weight gain during the first 3 weeks at the 15 % rate while weight gains were identical after 3 weeks. Phosphorus retention was decreased in the groups given 10 and 15% bran (Mitra, 1988). In Cirrhinus mrigala fingerlings fed ingredients at 4 % of wet body weight twice a day, wheat bran gave lower body weight and higher feed conversion ratio than maize guten feed and sunflower meal (Shabir et al., 2003).
In South American characids black pacu (tambaqui, gamitana) Colossoma macropomum and red pacu Piaractus brachypomus, cassava root, plantain fruit and peach-palm fruit (Bactris gasipaes) gave better growth performance than wheat bran and wheat middlings in diets containing 30 % of the test ingredient (Lochmann et al., 2009). In Colossoma macropomum, a diet including 23-25 % wheat bran formulated to containing 25 % protein and a DE of 11.3 MJ/kg gave better growth and feed conversion than diets containing 35 % protein, or than diets containing 25 % protein and lower DE (Gutierrez et al., 2009). Dry matter and crude protein digestibilities in red pacu Piaractus brachypomus were found to be lower for wheat bran than for soybean meal, fish and maize grain and the apparent DE of wheat bran was estimated at 7.5 MJ/kg, half of that of maize (14.0 MJ/kg), 2/3 that of soybean meal (10.0 MJ/kg) and much lower than that of fish meal (16.0 MJ/kg) (Fernandes et al., 2004).
In juvenile cichlids Sarotherodon melanotheron, maize bran was more suitable feed than chicken droppings and wheat bran. Survival rate with the by-products was always lower than with commercial feeds (Ouattara et al., 2005).
Mullet (Mugil auratus)
Mullet fry could be reared on a diet containing fish meal and wheat bran at the ration of 3:1 and fed at 10 % of body weight (Enbayah et al., 1987 cited by Hertrampf et al., 1989).
There is scarce literature on the use of wheat bran in crustaceans. Hertrampf et al., 2000 recommends of maximum inclusion rate of 2-5 %, though higher rates may be possible depending on the species.
In postlarval blue shrimp (Penaeus stylirostris), a diet containing 30 % mussel meal, 15 % squid meal, 5% soybean meal, 20 % fish meal and 22 % wheat bran supplemented with live Artemia nauplii the best growth and survival (Fenucci et al., 1984). Wheat bran fed alone was unsuitable for brine shrimp Artemia salina (Hertrampf et al., 2000).
Tables of chemical composition and nutritional value
|Dry matter||% as fed||87.0||1.1||83.3||92.2||20008|
|Crude protein||% DM||17.3||1.1||13.4||21.1||19566|
|Crude fibre||% DM||10.4||1.4||6.2||16.3||19416|
|Ether extract||% DM||3.9||0.6||2.0||6.4||9155|
|Starch (polarimetry)||% DM||23.2||4.1||13.0||38.7||17184|
|Total sugars||% DM||7.1||1.4||4.2||9.5||140|
|Gross energy||MJ/kg DM||18.9||0.2||18.6||19.5||60||*|
|Aspartic acid||% protein||7.0||0.4||6.0||7.6||22|
|Glutamic acid||% protein||18.9||1.8||16.0||21.9||21|
|Ruminant nutritive values||Unit||Avg||SD||Min||Max||Nb|
|OM digestibility, Ruminant||%||73.3||4.1||66.4||81.1||9||*|
|Energy digestibility, ruminants||%||71.4||3.1||66.8||76.5||8||*|
|DE ruminants||MJ/kg DM||13.5||*|
|ME ruminants||MJ/kg DM||11.0||0.6||10.2||11.8||8||*|
|ME ruminants (gas production)||MJ/kg DM||13.5||1|
|Nitrogen digestibility, ruminants||%||68.2||*|
|Nitrogen degradability (effective, k=4%)||%||79||*|
|Nitrogen degradability (effective, k=6%)||%||74||5||66||84||11||*|
|Pig nutritive values||Unit||Avg||SD||Min||Max||Nb|
|Energy digestibility, growing pig||%||57.0||7.0||46.5||71.0||17||*|
|DE growing pig||MJ/kg DM||10.8||5.2||9.0||33.2||18||*|
|MEn growing pig||MJ/kg DM||10.2||1.9||8.1||13.3||9||*|
|NE growing pig||MJ/kg DM||7.2||*|
|Nitrogen digestibility, growing pig||%||64.9||6.9||59.9||84.9||13||*|
|Poultry nutritive values||Unit||Avg||SD||Min||Max||Nb|
|AMEn cockerel||MJ/kg DM||7.8||1.6||5.3||10.6||16||*|
|AMEn broiler||MJ/kg DM||7.4||5.3||7.4||2||*|
|Rabbit nutritive values||Unit||Avg||SD||Min||Max||Nb|
|Energy digestibility, rabbit||%||62.6||5.2||59.4||69.0||3||*|
|DE rabbit||MJ/kg DM||11.8||1.0||10.7||13.7||12||*|
|MEn rabbit||MJ/kg DM||11.2||*|
|Nitrogen digestibility, rabbit||%||73.9||1.8||73.9||80.0||4||*|
The asterisk * indicates that the average value was obtained by an equation.
ADAS, 1988; Aderibigbe et al., 1993; AFZ, 2011; Albar, 2006; Anderson et al., 1991; Arosemena et al., 1995; Aufrère et al., 1991; Bach Knudsen et al., 2000; Bach Knudsen, 1997; Belibasakis, 1984; Betsha et al., 2009; Bhatti et al., 1995; Blas et al., 1998; Carré et al., 1986; Champ et al., 1989; Chandrasekharaiah et al., 2004; Chapoutot et al., 1990; Cilliers et al., 1998; CIRAD, 1991; CIRAD, 1994; Cirad, 2008; Darshan et al., 2007; De Boever et al., 1984; De Silva et al., 1990; DePeters et al., 1997; DePeters et al., 2000; Dewar, 1967; Djouvinov et al., 1998; Donkoh et al., 2009; Fadel, 1992; Fekete et al., 1986; Fialho et al., 1995; Forster et al., 1994; Furuya et al., 1988; Gippert et al., 1988; Gowda et al., 2004; Guillaume, 1978; Han et al., 1976; Hepburn et al., 1960; Hira et al., 2002; Huque et al., 1995; Jondreville et al., 2000; Kandylis et al., 1986; Karunajeewa et al., 1987; Khan et al., 1998; Kiiskinen, 1992; Krishna, 1985; Kuan et al., 1982; Landry et al., 1988; Laplace et al., 1989; Lekule et al., 1990; Lin et al., 1987; Macgregor et al., 1978; Madsen et al., 1984; Maertens et al., 1985; Maertens et al., 2001; Mariscal Landin, 1992; Maupetit et al., 1992; Melaku et al., 2003; Mondal et al., 2008; Morgan et al., 1975; Munguti et al., 2009; Nadeem et al., 2005; Naik, 1967; Najar et al., 1990; Narang et al., 1985; Noblet et al., 1997; Noblet et al., 2000; Nwokolo, 1986; Perez et al., 1984; Pozy et al., 1996; Qiao ShiYan et al., 2004; Ravindran et al., 1994; San Juan et al., 1993; Shi et al., 1993; Singh et al., 2006; Skiba et al., 2000; Smolders et al., 1990; Taghizadeh et al., 2005; Van Cauwenberghe et al., 1996; Vérité et al., 1990; Vervaeke et al., 1989; Wainman et al., 1979; Wiseman et al., 1992; Wolter et al., 1979; Yamazaki et al., 1986; Yin et al., 1993; Zhu et al., 1990
Last updated on 24/10/2012 00:45:20