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Buckwheat (Fagopyrum esculentum) grain and middlings

IMPORTANT INFORMATION: This datasheet is pending revision and updating; its contents are currently derived from FAO's Animal Feed Resources Information System (1991-2002) and from Bo Göhl's Tropical Feeds (1976-1982).

Datasheet

Description
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Common names 

Buckwheat, common buckwheat [English]; blé noir, blé de Barbarie, bucail, sarrasin [French]; Gwinizh-du [Breton]; pohanka [Czech]; boekweit [Dutch]; tattari [Finland]; echter Buchweizen, blenden, Brein, gemeiner Buchweizen, Haidl, Heidenkorn, Heidensterz, schwarzes Welschkorn, türkischer Weizen [German]; Φαγόπυρον το εδώδιμον [Greek]; grano saraceno [Italiano]; gryka [Poland]; trigo mouresco, trigo sarraceno [Portuguese]; Hrișcă [Romanian]; alforfón, trigo sarraceno [Spanish]; Karabuğday [Turkish]; Mạch ba góc, Kiều mạch [Vietnamese]; Bokwiet [Afrikaans]; Gandum kuda [Bahasa Indonesia]; حنطة سوداء [Arabic]; 蕎麥 [Chinese]; כוסמת [Hebrew]; कूटू [Hindi]; ソバ [Japanese]; 메밀 [Korean]; Гречиха посевная [Russian].

Synonyms 

Fagopyrum esculentum subsp. ancestralis Ohnishi, Polygonum fagopyrum L.

Description 

Buckwheat grain is the seed of the buckwheat plant (Fagopyrum esculentum Moench), an erect annual herb that grows mostly on poor soils. Buckwheat grain is edible and often used like cereal grains such as wheat or maize. For that reason, buckwheat is often referred to as a cereal though it is from the Polygonaceae family and not from the Poaceae family like proper cereals. As its composition is close to that of cereals, buckwheat grain can be used as feed for all classes of farm animals (Jansen, 2006).

The buckwheat plant yields several products (Steadman et al., 2001):

  • Buckwheat grain (seed): it can be used whole, dehulled or further processed to produce groats or flour.
  • Buckwheat hulls: they result from the dehulling process.
  • Buckwheat bran; it results from the milling of the grain. Its composition depends on whether or not the grain has been dehulled prior to milling. Bran from whole grains include hull fragments and may contain high amounts of fibre.
  • Buckwheat forage (see Buckwheat (Fagopyrum esculentum) forage datasheet)

Morphology

Buckwheat is an erect annual herb that grows up to 1.2 m high and has an indeterminate growth habit. The root system consists in a shallow taproot and spreading secondary roots that can go 1 m deep (Kammermeyer, 2016). The stems are hollow and triangular. Its leaves are alternate, simple and entire, with stipules. Lower leaves are petiolated while upper ones are almost sessile. The leaf blade is triangular to cordate, 2-10 cm long x 2-10 cm broad. The inflorescence is an axillary or terminal cluster of flowers, combined in false racemes. The flowers are regular, small-sized, rose-red to white in colour. The fruit is a typical triangular, winged nutlet, 5-7.5 mm x 3 mm, grey-brown, dark brown to black in colour. The seed is pale green turning reddish brown almost the same size as the fruit (Jansen, 2006).

Uses

Buckwheat seeds are edible and can be eaten whole or dehulled, ground into flour or groats depending on the final intended use. The flour can be used to make pancakes in Brittany and crozets in the French Alps. Buckwheat seeds have regained interest because of their gluten free proteins sought after by many consumers with gluten intolerance. It is reported to have prophylactic values, such as an anthelminthic effect when fed to livestock (Goncalves et al., 2016; Christa et al., 2008). Buckwheat seeds and whole plants can be fed to all classes of livestock which eat it readily.

Distribution 

Buckwheat originated from Asia. It was domesticated first in the South of China as early as 2000 to 3000 BCE. It was later introduced to other Asian countries, southward crossing the Himalayas and eastwards to Japan. The arrival of buckwheat in Europe followed the silkroad and its cultivation became popular during the early Middle ages. During the 17th century, European emigrants brought buckwheat to the Americas and to South Africa. It is now grown worldwide.

Buckwheat production reached its maximum during the 19th century. It later declined due to the emergence of cereal crops that made more benefit of fertilizers and had greater yields. Total crop area was 2.5 million ha in 1961 and it was down to 1.44 million ha in 2010 (Jacquemart et al., 2012). Since the 2000s, there has been a renewed interest in buckwheat due its favourable nutrient properties for human consumption, such as its gluten-free proteins and antioxidative substances. It has been reported to be a good cover crop (Jacquemart et al., 2012). Since 2010, buckwheat crop area has been steadily increasing and was 3.94 million ha in 2017 (FAO, 2019). In 2017, buckwheat grain production worldwide was about 3.82 million t (FAO, 2019). Before the 1970s, 75% of the US buckwheat production were used for livestock feeding but the value of buckwheat grain for human diet resulted in lower use in animal feeding (Oplinger et al., 1989).

Buckwheat is found in temperate and subtropical areas. It can be cultivated at higher elevations in the tropics (1500 m altitude in Ethiopia, for example). Buckwheat can grow where day temperatures are in the 18-30°C range where night temperatures are 5-10°C lower (Jansen, 2006). It requires a dry period at maturity and harvest but it is sensitive to drought at earlier stages because of its shallow roots. If drought occurs during blooming stage, seed production is impaired. Buckwheat does very well on low N, light sandy soils with neutral to slightly acidic pH. It is particularly adapted to recently cleared infertile fields, drained marshland or acidic soils with a high content of decomposing organic matter. It does not well on rich soils since lush growth causes lodging and reduces seed set. However, if it is grown to produce biomass and not seed, rich heavy soils keep being valuable (Jacquemart et al., 2012).

Forage management 

Buckwheat (Fagopyrum esculentum) is a fast growing plant that can be cultivated as a summer or a winter crop in rotation with cereals or also be intercropped with vegetables (Jansen, 2006). However, it is not recommended to sow buckwheat in mixed stand with legumes. Buckwheat reaches its full height only 4-6 weeks after sowing and sets seeds within 70-130 days after emergence. The indeterminate growth habit of buckwheat is a constraint of the crop as it is never easy to determine when best harvest of the grain can be obtained.

Cultivation

Buckwheat seeds should be sown on a clean 5 cm depth firm, well-prepared seed-bed. It can be drilled at 40-60 kg/ha to 2- 4 cm deep in rows spaced 30 cm apart or it can be broadcast at higher density (+10-20 kg seeds/ha) and then harrowed to cover with topsoil (Jansen, 2006). Though weeds are generallly not a problem, fast growing weeds may however be an issue and this is alleviated by sowing at higher density and harrowing 4 weeks after sowing. This operation removes weeds and buckweat plant but the high density of buckwheat allows it to remain in good quantity. If sown at lower density the plant will make more branches and seeds.

Yields

In Turkey, a mean grain yield ranged from 1460 to 1590 kg/ha (Kara, 2014). In the USA, yields ranging from 1200 to 1700 kg/ha were reported (Björkman, 2010). Under harsh conditions of South Italy, buckwheat grain yieds were comprised between 0.76 tonne/ha and 1.53 tonnes/ha (Brunori et al., 2005).

Harvest

Determining time of harvest is uneasy because of the undeterminate habit of the plant. The plant may still be green when the seeds are mature. It is recommended to examine the grains when the crop enters the 10th and 11th week after sowing. Harvest should start when 3/4 of the seeds are brown and the groat inside is firm. If harvest is delayed, the plant is at lodging risk since the seeds get heavy, the leaves are falling and the wind (end of summer) is stronger. Over-mature seeds are also prone to shattering which may result in grain losses (Björkman, 2010)

The main concerns for harvest timing are lodging and shattering. The risk of lodging increases quickly as the seeds get heavier, the leaves fall, and the winds become stronger. Shattering occurs in over-mature plants and causes much of the grain to be lost if harvest is delayed too long. The harvest window is therefore fairly brief (Björkman, 2010).

Environmental impact 

High quality cover crop and rotational effect

Buckwheat germinates and grows quickly, soon developing a dense, shading canopy that smothers weeds effectively (Kammermeyer, 2016; Valenzuela et al., 2002). It also produces high amount of biomass that can be ploughed into the soil for high N and high P manure (Jacquemart et al., 2012). Buckwheat has an excellent "rotational effect". It is also a phosphorus scavenger: its roots exsude chemical substances that extract inorganic phosphorus from the soil and they make reserves of phosphorus. Roots residues thus make phosphorus more available to the next crop and also return considerable levels of phosphorus to the soil (Valenzuela et al., 2002).

Weed and diseases control

Buckwheat plant has some allelopathic properties that prevent weed development (Jacquemart et al., 2012). Buckwheat residues were also reported to have allelopathic effects on weeds (Valenzuela et al., 2002). Spreading 2 tonnes of buckwheat pellets before rice plantation was found to reduce weed by 80% in rice field and thus to increase rice yield by 20% (Eom et al., 1999; Iqbal et al., 2002). Buckwheat also decreases disease load (Jacquemart et al., 2012).

Interaction with insects

Buckwheat with its continuous blooming attracts many kinds of insects including pest predators like syrphids. It is a good foraging plant for bees that make tasteful honey from its nectar. It has been reported taht 1 ha of buckwheat could provide 125-300 kg honey. Buckwheat long lasting flowering period is also valuable for beekeepers as the bees still find food on buckwheat when other melliferous plants have disappeared (Naukim, 1998 and Olson, 2001 cited by Jacquemart et al., 2012).

Nutritional aspects
Nutritional attributes 

Buckwheat grain is not a cereal grain but its nutritive characteristics  are similar to those of cereal grains.

Buckwheat grains are rich in starch (50 to 70% of the dry mass) (Linh et al., 2014; Christa et al., 2008). The protein content has been reported to be in the range of 10-15% and the NDF content in the range of 20-25% (Linh et al., 2014; Leiber et al., 2012; Amelchanka et al., 2010).

Compared to maize and wheat, buckwheat grains are richer in lysine and arginine (Linh et al., 2014; Christa et al., 2008). Content in essential minerals as magnesium, copper, potassium, and phosphorus are also interesting in buckwheat grains.

Buckwheat contains also different secondary metabolites as vitamins and polyphenols, which contribute to animal health and product quality. All parts of buckwheat plant contain high concentrations of condensed tannins and total phenolic compounds; rutin and quercetin being the main phenolic compounds (Herremans et al., 2018; Christa et al., 2008; Kalinova et al., 2006). In vitro anthelmintic and antioxidant effects of buckwheat grains linked to its richness in secondary compounds have been demonstrated (Goncalves et al., 2016).

In comparison to cereals, buckwheat grains present higher contents of B vitamins (Linh et al., 2014; Christa et al., 2008). High concentrations in α-tocopherols of buckwheat whole plants have also be reported (Maxin et al., 2017; Kalinova et al., 2006).

Potential constraints 

Skin sensitization

Buckwheat contains fagopyrin, a flavonoid that causes skin sensitization in animals fed on buckwheat. The content of fagopyrin is higher in green parts of the plants and cattle, sheep and goats are thus more likely to suffer from this health condition than monogastric animals fed on grain. Skin rash can develop on light-colored animals if they are fed during a long time on a ration that contains more than 20-25% of the concentrate content in buckwheat and if they are in the sun (Lardy et al., 2009; Björkman, 2010).

Ruminants 

Buckwheat grain is readily eaten by cattle (Björkman, 2010). 

Grain

Scarce studies suggested that buckwheat grains were suitable for ruminant feeding. Buckwheat grain should be ground for all classes of livestock (Lardy et al., 2009).

Cattle

In cow rations, buckwheat grain inclusion should be limited to 20-25% of the concentrate content in order to prevent photosensitization (Lardy et al., 2009). Intake and milk yield did not change when dairy cows received buckwheat grains (94 g/kg DM) instead of concentrate (Amelchanka et al., 2010).

It has been suggested that provision of quercetin or rutin through buckwheat feeding in cows could promote animal health and reduce methane emissions without deleterious effects on ruminal fermentations nor subsequent effects on volatile fatty acids(lower stress during early lactation)(Berger et al., 2015). 

Sheep

Sheep could be fed on buckwheat, wheat or oat grains without showing differences in intake and in wool growth performance between grains (Mulholland et al., 1995). However, the digestible energy of the diet with buckwheat was lower than diet with wheat, but higher than diet with oat.

Pigs 

Grain

Buckwheat grain is used in pig feeding as a source of energy with a relatively low protein content but with a valuable aminoacid profile (high in lysine and methionine) for pigs (Taranenko et al., 2016). Buckwheat grain has also lower digestibilities of dry matter, energy and protein than those of cereal grains (60-65% vs. 80-85%)(Taranenko et al., 2016; Duval, 1995). Because of fagopyrin content in buckwheat grain and subsequent skin sensitization, buckwheat grain is not recommended for light-coloured organic pigs that stay outside (Blair, 2007).

It was shown that buckwheat grain could replace wheat grain in diets for growing pigs containing 12 % CP without modifying nutrient digestibility and growth performance provided it could be supplemented with protein source (meat or sunflower meal)(Anderson et al., 1984; Farrell, 1978). However, at high dietary proportions of buckwheat (above 60%), digestibility was impaired and the acceptablity of buckwheat in pigs was poor. The growth performance of pigs fed on buckwheat grain as a sole feed were lower than with wheat-only diets (Farrell, 1978; van Wyk et al., 1952).

Though it had been hypothesized that the high concentrations of antioxidative phenols and vitamins (Kalinova et al., 2006; Wijngaard et al., 2006) could be beneficial by improving the antioxidative stability of pork; it could not be proven (Leiber et al., 2016). 

Bran

In 2010, a phenol-rich buckwheat bran included in pigs diets had no effect on fatty acid profiles or oxidative stability in the muscle (Flis et al., 2010).

Poultry 

Defective grains of buckwheat and waste products from processing like buckwheat bran or hulls are used as feed in poultry farming (Taranenko et al., 2016; Benvenuti et al., 2012).

Buckwheat grain is mainly a source of energy for poultry (Leiber et al., 2016). Though it has relatively low protein content, its amino acid profile, high in lysine, methionine and threonine makes buckwheat grain a suitable protein source for poultry (Leiber et al., 2016). The fibre contained in the hulls/bran of the grain are not considered a limiting factor.

The risk of skin sensitization due to fagopyrin exists in birds fed on buckwheat but is considerably lower than in cattle as the fagopyrin is mainly contained in the green parts of the plant and not in the seeds (Leiber et al., 2016).

Broilers

Buckwheat could be included in broilers diet up to 40% dietary level (DM) in order to replace wheat or maize grain without compromising growth rates, slaughter weights, and feed conversion ratios (Leiber et al., 2009; Jacob et al., 2008; Gupta et al., 2002). A former study had reported that buckwheat as a main component of broiler diet was superior to wheat and oats cereals, regarding N retention, growth rate and feed conversion (Farrell, 1978). The diet with buckwheat resulted however in poorer performance feed conversion ratio than the commercial diet(Farrell, 1978).

Above 40% DM dietary level, buckwheat yields poorer feed conversion ratio due to reduced body weight gain (Gupta et al., 2002) or higher feed intake (Jacob et al., 2008). This could be due to fibre level brought by buckwheat hulls in the diet (Leiber et al., 2016).

High tocopherol concentrations in buckwheat (Wijngaard et al., 2006) may lead to significantly increased tocopherol concentrations in broiler meat, when buckwheat replaces wheat in the diet (Leiber et al., 2009). Feeding buckwheat was thus reported to improve the nutritional value of poultry meat.

Laying hens

Buckwheat grain

Laying hens fed on whole grain buckwheat or shelled buckwheat at a dietary level of 40% dry matter had similar egg production and significantly heavier eggs compared to those on wheat-based control diet (Leiber et al., 2011). Former results obtained with a less performing genotype were not in accordance with this promising results (Farrell, 1978).

Buckwheat grain was reported to improve egg quality. Feeding whole buckwheat grains was reported to improve the shell strength of the eggs (Leiber et al., 2011). The tocopherol concentration in egg yolk may be more than doubled when whole grain buckwheat replaces wheat (Leiber et al., 2011).

Buckwheat bran

Partially substituting maize and soybean with buckwheat bran (30% DM) in a diet for layers maintained their performance on the same level as the control (Benvenuti et al., 2011).

Rabbits 

Buckwheat grain

Buckwheat (Fagopyrum esculentum) grain is known since a long time as a grain normally usable in rabbit feeding (Voris et al., 1940). It can easily replace a mixture of maize + wheat bran, in balanced diets for growing rabbits, for example up to 14% of the diet, without modification of growth rate, feed efficiency or slaughter yield (Furlan et al., 2006). With this type of substitution (wheat byproducts + maize), the incorporation level of buckwheat grain in the diet was increased up to 60% without modification of growth rate, energy or crude protein digestibility, but with the increase of the buckwheat proportion in the diet, ADF digestibility was impaired (Tor-Agbidye et al., 1990).

In a study conducted in India, buckwheat grains were incorporated in a concentrate proposed ad libitum to growing rabbits together with freshly cut soybean fodder also ad libitum. Even with the highest level of buckwheat tested (78,5% of the concentrate), there were no significant differences in growth rate, dry matter intake and feed efficiency values in grower rabbits fed either control or buckwheat based test diets (Gupta et al., 2006)

If buckwheat grains are available for animal feeding, for its inclusion in balanced rabbit diets, it must be considered in the same manner than true cereals, but with a noticeable difference in the protein amino-acids equilibrium. Contrary to that of all cereals, buckwheat protein (10-15% DM - Christa et al., 2008)) is rich in lysine (6 to 7 g/16gN) covering about 120% of rabbits requirements, but deficient in sulphur amino acids (2,5-3,4 g/16gN) covering only about 75 to 80% of rabbits requirements (Javornik et al., 1984; Zhao et al., 2004, Lebas, 2013). Otherwise buckwheat grain digestible energy content is about 14.0 to 14.4 MJ/kg DM according to authors (Voris et al., 1940, Furlan et al., 2006). Lipids content of buckwheat grain is moderate (~2,5-2,8% DM), but theses lipids are rich in linolenic acid (40% of fatty acids) and contain an appreciable proportion of linolenic acid (5-6%) (Min et al., 2004).

Buckwheat middlings

As mentioned for the whole plant, no information seems available in the international literature of the use of buckwheat middlings in rabbit feeding. However buckwheat middlings are frequently used in ruminant feeding with success (Scheucher, 2004). Thus middlings could be considered as potential sources of raw materials usable in rabbit feeding mainly a source of protein: 33-34% crude protein with a low content of fibre (10% ADF in DM) (Waller, 2010; Ratan et al., 2011).

A special mention must be done to buckwheat hulls (or husks), which are generally used as fuel by farmers or to fulfil pillows, but also used to feed ruminants when the stock of buckwheat straw is exhausted (Ratan et al., 2011; Zemnukhova et al., 2004, ). This byproduct is mainly composed  of fibre (80% total fibre and about 30% lignin) (Ciepielewska et al., 2004). Thus, it may be considered as a potential source of lignin for rabbit balanced diets (one of the richest among all raw material available). However new direct experiments should be done with buckwheat hulls, since ancient experiments mentioned physiological alterations following buckwheat husks distribution to rabbits, rats or mice (true effect of buckwheat husks or consequence of a mycotoxins present in the husks batch used for the experiment ?)(Kubo et al., 1939; Kubo et al., 1938).

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DATASHEET UNDER CONSTRUCTION. DO NOT QUOTE. https://www.feedipedia.org/node/25140 Last updated on August 20, 2019, 19:46