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Buckwheat (Fagopyrum esculentum) forage

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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].

Description 

Buckwheat (Fagopyrum esculentum Moench) is an erect annual herb grown worldwide for its edible seed, which is used like cereal grains such as wheat or maize. While the plant is primarily grown for grain production, its foliage can be fed to livestock (Jansen, 2006):

  • The whole plant can be grazed, or cut and fed in different forms: fresh, hay or silage.
  • Buckwheat straw is the crop residue obtained after the grain has been harvested and separated from the plant. The straw is often used for bedding but can be used as fodder.
  • Buckwheat stover/stubbles are the leftovers that can be grazed in the field after grain harvest (Lardy et al., 2009),

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 forage can be fed to livestock that eat it readily. It can be fed green, made into hay or ensiled. Buckwheat make a valuable cover crop and provides green manure (Jacquemart et al., 2012; Jansen, 2006). Because buckwheat is primarily grown for grain, it tends to be used for forage only when agronomic and economic circumstances may make forage production more valuable than grain production. In the USA, if seed set appears compromised by late August or early September, the forage value may be higher than the grain value. Likewise, if hay prices are high because of local crop failures, using buckwheat for forage may be a good idea (Björkman et al., 2010). Buckwheat can be used as a cultivation of substitution to maize that was not planted due to adverse weather (Kammermeyer, 2016). In some countries, like Bhutan, buckwheat crop residues can be an important feed (Wangchuk et al., 2008).

Distribution 

Buckwheat originated from Asia. It was domesticated first in southern 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 is a fast-growing plant that can be cultivated as a summer or a winter crop in rotation with cereals or 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, firm, well-prepared, 5 cm-deep seed-bed. It can be drilled at 40-60 kg/ha to 2-4 cm depth 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 generally not a problem, fast-growing weeds may be an issue: this is alleviated by sowing at higher density and harrowing 4 weeks after sowing. This operation removes weeds and some buckweat plants 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, buckwheat yield of fresh forage was above 27 t/ha and hay yield was about 7.5-8.5 t/ha. Yields increased by delaying harvest times (Kara, 2014). In Bhutan, buckwheat straw DM yield was 1 t/ha (Wangchuk et al., 2008).

Harvest

When buckwheat is intended as a forage crop, it should be cut early in flowering (5-6 weeks after sowing) as its protein content and digestibility are still high. Waiting longer to cut decreases quality and does not increase yield substantially (Björkman et al., 2010).

Environmental impact 

Buckwheat present several environmental advantages, and it has been suggested that using it as an animal feed could help to counteract the food-feed competition, particularly as it can provide a second harvest on arable land under temperate conditions (Amelchanka et al., 2010).

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 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 a phosphorus scavenger: its roots exsude chemical substances that extract inorganic phosphorus from the soil. Roots residues make phosphorus more available to the next crop and return considerable levels of phosphorus to the soil (Valenzuela et al., 2002).

Weed and diseases control

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

Interaction with insects

With its continuous blooming, buckwheat 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: honey production averages 70–100 kg/ha and reaches 150–300 kg/ha for the best cultivars. Its long lasting flowering period is valuable for beekeepers as the bees can still find food on buckwheat when other melliferous plants have disappeared (Naumkin, 1998; Olson, 2001; Cawoy et al., 2008).

Nutritional aspects
Nutritional attributes 

Fresh forage

Fresh buckwheat forage has a protein content ranging from 10% to about 20% DM, depending on maturity (Duval, 1995; Ratan et al., 2011). Even wider ranges have been reported in the USA, from less than 4% protein to more than 25% (Björkman et al., 2010). The protein content is high at leafy growth stage (19% DM) and declines rapidly with maturity (12% DM), while the fibre content start relatively low (ADF 29% DM) and then increases (ADF 47% DM) (Leiber et al., 2012; Kälber et al., 2011; Kälber et al., 2014; Maxin et al., 2017). The protein of buckwheat leaves, like that of the grain, is relatively rich in lysine (5.8% of the protein) and poor in sulphur amino acids (Lahanov et al., 2004).

Straw

Like grass straws, buckwheat straw is mostly rich in fibre (NDF > 70% DM) and poor in protein (4-5% DM) though it may contain a little more protein than wheat or barley straw.

Potential constraints 

Skin photosensitivity

The buckwheat plant contains fagopyrins, a group of phototoxic substances that cause skin photosensitivity, eruptions on the skin, itching behavior, allergic reactions and even death after ingestion (Wender et al., 1943; Leiber, 2016). Light-coloured animals are particularly susceptible to that risk if they are fed buckwheat for a extended period and exposed to sunlight, and a maximum of 30% buckwheat forage in the diet is recommended in that case (Lardy et al., 2009; Björkman et al., 2010). Because fagopyrins are more present in the green plant than in the grain, ruminants fed buckwheat forage are more at risk than pig and poultry fed on grain. In southeastern Lithuania, only coloured pigs could be pastured on buckwheat and fed buckwheat chaff without suffering from increased sensitivity to sunlight and the breeding of coloured native pigs was most prolonged in this region (OSU, 1996). 

It should be noted that, while observations about fagopyrism go back to the early 18th century, there are actually few reported cases, which are old and partly anecdotal, so that a scientific update should be necessary to define dietary thresholds (Leiber, 2016). In northern regions where sunlight is limited during winter and where few quantities of buckwheat forage are available, this concern may be relatively small (Björkman et al., 2010).

Tannins and phenolic compounds

All parts of buckwheat plant contain high concentrations of condensed tannins and total phenolic compounds. Rutin and quercetin are the main phenolic compounds (Herremans et al., 2018; Christa et al., 2008; Kalinova et al., 2006).

Ruminants 

Buckwheat forage is palatable and can be of good qualily and digestible but only before grain maturity, so fresh forage or pasture is generally not widely available since the plant is grown for grain. In some countries, notably in the Himalayas, buckwheat straw is a common feed.

Digestibility

In vitro organic matter digestibility of fresh buckwheat forage declines with maturity with 91% and 78% at vegetative and flowering stage respectively (Herremans et al., 2018).

Fresh forage

Dairy cows

When mixed with ryegrass as part of a cow diet, fresh buckwheat resulted in higher intake and similar milk yield in comparison to ryegrass alone. It improved the transfer of alpha-linolenic fatty acid from the diet to milk. However, milk yields were lower when buckwheat was fed at flowering stage than when fed at vegetative stage (Kälber et al., 2014; Kälber et al., 2011).

Other ruminants

Deers readily graze buckwheat and they can even overgraze it, but it make take up a year or two before they discover and begin using buckwheat plots (Kammermeyer, 2016).

Silage

Dry matter intake and milk yield and composition of dairy cows fed buckwheat silage were similar to dairy cows fed ryegrass silage (Kälber et al., 2012a). However, milk from dairy cows receiving buckwheat had higher proportion in linoleic acid and total PUFA compared to milk from dairy cows receiving ryegrass silage (Kälber et al., 2013). For cheese-making, feeding cows with buckwheat silage shortened rennet coagulation time of the milk by 26% and tended to increase curd firmness by 29% (Kälber et al., 2013).

Hay

Buckwheat hay can be fed to livestock and was reported to be palatable (Lardy et al., 2009).

Crop residues: straw and stubbles

Buckwheat straw can be used as bedding material but livestock often eat it instead due to its palatability. It should be limited to 25% of the ration (Lardy et al., 2009). In Tibet, buckwheat straw, mixed with barley or wheat, is used as animal feed. It is stored and fed in winter and spring (Scheucher, 2004). In Bhutan, buckwheat straw is a common feed in higher elevations (Wangchuk et al., 2008).

Grazing buckwheat stubbles resulted in low acceptability and nutritive value in sheep (Mulholland et al., 1979).

Pigs 

In southeastern Lithuania, a buckwheat-growing region, pigs used to be fed with buckwheat chaff and pasture, which led farmers to breed coloured  and less photosensitive animals (OSU, 1996).

Poultry 

Buckwheat could be grown in association with phacelia (Phacelia tanacetifolia) and flax (Linum usitatissimum) and grazed by free range poultry. This mixture of forbs was well accepted by the hens without affecting performance (Horsted et al., 2006).

Rabbits 

No information seems available in the international literature of the use of buckwheat as green or dry (hay) forage in rabbit feeding. Wild rabbits have been observed to damage buckwheat crops in Tibet (Scheucher, 2004), which indicates that buckwheat forage is palatable to them and that it could be potential source of forage for rabbits. Buckwheat straw is used for ruminants and could thus be fed to rabbit as a source of fibre.

Nutritional tables

Avg: average or predicted value; SD: standard deviation; Min: minimum value; Max: maximum value; Nb: number of values (samples) used

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 15.9 11.3 9.5 30 7  
Crude protein % DM 14.1 5.5 3.1 25.7 28  
Crude fibre % DM 28.4         *
Neutral detergent fibre % DM 46.3 7.3 30.5 58.3 14  
Acid detergent fibre % DM 33.9 5.5 22.6 43.5 17  
Lignin % DM 7.7 2.1 4.9 9.9 5  
Ether extract % DM 0.9   0.2 1.8 4  
Ash % DM 11.4 3.1 5.8 15.2 9  
Gross energy MJ/kg DM 17.6         *
               
Amino acids Unit Avg SD Min Max Nb  
Alanine g/16g N 6.3       1  
Arginine g/16g N 6.1       1  
Aspartic acid g/16g N 10.8       1  
Glutamic acid g/16g N 13.7       1  
Glycine g/16g N 5.8       1  
Histidine g/16g N 3.4       1  
Isoleucine g/16g N 4.3       1  
Leucine g/16g N 9.6       1  
Lysine g/16g N 5.8       1  
Methionine g/16g N 1.3       1  
Phenylalanine g/16g N 6.2       1  
Phenylalanine+tyrosine g/16g N 11.1         *
Proline g/16g N 3.5       1  
Serine g/16g N 5       1  
Threonine g/16g N 5.1       1  
Tyrosine g/16g N 4.9       1  
Valine g/16g N 5.5       1  
               
Fatty acids Unit Avg SD Min Max Nb  
Myristic acid C14:0 % fatty acids 1.4   0.3 2.4 4  
Palmitic acid C16:0 % fatty acids 15.6   14.5 17.5 4  
Palmitoleic acid C16:1 % fatty acids 3.1   2.8 3.5 4  
Stearic acid C18:0 % fatty acids 0.8   0 2.3 4  
Oleic acid C18:1 % fatty acids 6.2   3.5 10.6 4  
Linoleic acid C18:2 % fatty acids 24.5   23.1 27.6 4  
Linolenic acid C18:3 % fatty acids 37.2   31.6 41.4 4  
               
Minerals Unit Avg SD Min Max Nb  
Calcium g/kg DM 25.6 5.6 19.9 34.3 10  
Phosphorus g/kg DM 2.4 0.4 2 2.9 10  
Potassium g/kg DM 29.3 14.7 13.6 57.6 15  
Magnesium g/kg DM 4.7 1.4 3.1 6.4 10  
Manganese mg/kg DM 51 8 39 61 10  
Zinc mg/kg DM 83 28 44 126 10  
Copper mg/kg DM 7 1 6 9 10  
Iron mg/kg DM 353 70 235 436 10  
               
Secondary metabolites Unit Avg SD Min Max Nb  
Tanins, condensed (eq. catechin) g/kg DM 4   3 6 4  
               
Ruminant nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 62.9         *
Energy digestibility, ruminants % 60.1         *
DE ruminants MJ/kg DM 10.6         *
ME ruminants MJ/kg DM 8.5         *

The asterisk * indicates that the average value was obtained by an equation.

References

Amelchanka et al., 2010; Björkman et al., 2010; Görgen et al., 2016; Kälber et al., 2011; Kälber et al., 2014; Kara, 2014; Lahanov et al., 2004; Leiber et al., 2012

Last updated on 27/08/2019 16:50:13

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 87.2   83.3 91 2  
Crude protein % DM 4.6   4 5.2 2  
Crude fibre % DM 50.4       1  
Neutral detergent fibre % DM 73       1  
Acid detergent fibre % DM 56   49 62.9 2  
Lignin % DM 10.7       1  
Ether extract % DM 1.2   0.7 1.7 2  
Ash % DM 7.2   6.9 7.5 2  
Gross energy MJ/kg DM 18.7       1 *
               
Ruminant nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 36.5       1  
Energy digestibility, ruminants % 33       1 *
DE ruminants MJ/kg DM 6.2       1 *
ME ruminants MJ/kg DM 4.9         *
Nitrogen digestibility, ruminants % 5.9       1  
               
Rabbit nutritive values Unit Avg SD Min Max Nb  
Energy digestibility, rabbit % 21.8         *
DE rabbit MJ/kg DM 4.1         *
MEn rabbit MJ/kg DM 3.9         *
Nitrogen digestibility, rabbit % 61.2         *

The asterisk * indicates that the average value was obtained by an equation.

References

Açar et al., 2015; Deoka et al., 1991

Last updated on 27/08/2019 16:56:03

References
References 
Datasheet citation 

Heuzé V., Tran G., Maxin G., Lebas F., 2019. Buckwheat (Fagopyrum esculentum) forage. Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. https://www.feedipedia.org/node/25478 Last updated on August 27, 2019, 17:00