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Foxtail amaranth (Amaranthus caudatus)

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
Click on the "Nutritional aspects" tab for recommendations for ruminants, pigs, poultry, rabbits, horses, fish and crustaceans
Common names 

Foxtail amaranth, Inca-wheat, Love-lies-bleeding, purple amaranth, cat-tail, red-hot-cattail, tassel-flower, tumbleweed, velvet flower, foxtail [English], amarante caudée, amarante queue-de-renard, discipline des religieux, queue de renard [French]; Gartenfuchsschwanz, Inkaweizen [German]; moncos-de-Peru [Portuguese]; coimi, cuipa [Quichua (Peru)]; achita, bledo francés, kiwicha, quilete, trigo del Inca [Spanish]; rävsvans [Swedish]; bayam ekor kucing [Indonesian]; bayam selaseh [Malaysian]; phakkhom-baidaeng [Thai]; rau dền duôi [Vietnamese].

Description 

Foxtail amaranth (Amaranthus caudatus) is one of the most popular domesticated amaranths that has been cultivated for a long time as a multipurpose pseudocereal of high nutritive value, vegetable and as an ornamental plant(eFloras, 2021).  Foxtail amaranth (Amaranthus caudatus) belongs, with Amaranthus cruentus and Amaranthus hypochondriacus to the group of grain amaranths (Brenner et al., 2000). The plant residue after grain harvest may be fed to livestock or used to thatch. 

Morphology

Foxtail amaranth (Amaranthus caudatus) is an annual erect herb 0.5-1.5 (-2.5) m in height, commonly reddish or purplish in colour throughout. The root system consists in a short enlarged taproot and secondary roots that explores deeper soil layers (NRC, 1989). The stem is rather stout, moderately branched, glabrous or thinly furnished with rather long hairs. The leaves are simple and entire, spirally arranged, borne on petiole up to 8 cm long shorter than the blade. The leafblade is broadly ovate to rhomboid-ovate or ovate-elliptical, 2.5-15 (-20) cm long × 1–8 cm broad, glabrous or sparsely hairy below, pinnately veined. The inflorescence is large (0.9  to 1.5 m), robust, and complex, consisting of numerous agglomerated cymes arranged in axillary and terminal spikes, the terminal one drooping or nodding. The inflorescence is showy, very versatile in colour, ranging from red, purple to white and less often green, silvery green or yellow. It may look like red cat's tail, hence one of its vernacular name: "cat's tail" or "red-hot-cattail". The flowers are unisexual, sessile: male flowers mostly at the apex of the spike. The fruits are ovoid-globose, one-seeded capsules, about 1.5-2.5 mm long, almost smooth or slightly furrowed, abruptly narrowed to a short thick beak. The seeds are nearly globose, 1-1.5 mm long, very light, smooth and shining, very variable in colour (from ivory, yellowish white to reddish brown or dark brown) (eFloras, 2021; Agong, 2006; NRC, 1989). The foxtail amaranth 1000-seed weight is 0.5-1.1 g (Agong, 2006)

Uses

Foxtail amaranth is mainly used as a source of food in India and South America (Agong, 2006). In Peru, foxtail amaranth is known as kiwicha. It is the most important Andean species of the genus Amaranthus. Foxtail amaranth seeds are reported to be flavorful and highly nutritious and, unlike quinoa do not contain saponins. The seeds are used to feed infants and pregnant women, invalids and elderly people (NRC, 1989). They can be used in several recipes. When heated, they produce a crunchy nutty "popcorn", they can be used as a snack, as a cold cereal with milk and honey, in sweets, or as a “breading” on chicken or fish. The grain can be ground into flour, rolled into flakes, “puffed,” or boiled for porridge. The flour of foxtail amaranth grains can be blended with other ceral flours to improve their nutritive value (higher protein, better aminoacid balance and higher vitamin content). It enters in bakery specialties. In Ethiopia, it is considered a famine food in times of scarcity and an ingredient of injera in combination with teff in times of abundance (Agong, 2006). The plant contains pigments that could be used for food colouring. Young leaves and stems of foxtail amaranth can be boiled as greens, like spinach (NRC, 1989). Although they are not reported in statistics, the various amaranths may actually be the most widely grown vegetable crop in the humid tropics( NRC, 1989). After grain harvest, the plant residues can be fed to livestock or used for thatching. All parts of foxtail amaranth have ethnomedicinal applications and have been reviewed for their potential benefits (anti-diabetic, anti-hyperlipidemic, anti-atherogenic, regulator of arterial pressure, cardioprotective) in human health (Martinez-Lopez et al., 2020; Agong, 2006). 

 

Distribution 

Foxtail amaranth (Amaranthus caudatus) is thought to have originated in South America from some wild race of the A. hybridus aggregate. Foxtail amaranth is believed to have been fully domesticated in South America for a long time. It has been found in Andean tombs more than 4,000 years old (Coons, 1982). Foxtail amaranth, called kiwicha, was used by the Incas, Aztecs, and other pre-Columbian peoples, as a staple grain. It was once almost as widely dispersed throughout the Americas as corn. After the Conquista, it has been replaced by colonists' cereals,and only in the 1970's, it started to be grown again in the Andes and other parts of the world (NRC, 1989). It was introduced to Europe as an ornamental during the 17th century and to Asia by 18th century. In the mid 20th, amaranth production gained renewed interest among organic producers in the US as it was referred to as a healthy and highly nutritious plant (Brenner et al., 2000).

Numerous infraspecific entities that are mostly of horticultural importance have been described within A. caudatus (eFloras, 2021).

Foxtail amaranth can grow on a wide range of conditions, it is tolerant of drought and heat. As a C4 carbon-fixing plant, foxtail amaranth is particularly efficient at high temperature, in bright sunlight, and under dry conditions. In the Andean region, it does well in places where conventional grain crops fail. It is a pionneering plant in new environments where it has been introduced (NRC, 1989). It can become a weed in crops or in degraded land around the crops but is seldom referred to as an invasive or noxious weed (eFloras, 2021).

Foxtail amaranth keeps doing well under very variable soil nutrients levels. In Peru, foxtail amaranth can be grown with supplemental irrigation and manure fertilizer (Agong, 2006).

There is no worldwide data on amaranth production (D'Amico et al., 2017). The main amaranth-producing countries have been reported to be the tropical regions of South America, Africa (especially for leaves of the amaranth plant), Central, and Southeast Asia (especially India, Bangladesh, and Sri Lanka), and Caribbean (Agong, 2006). In the highlands of Nepal, amaranths are most common at elevations between 2000 and 3000 metres above sea level (Khadka, 1987). Amaranths are also grown to a minor extent in the warmer regions of North America. In Europe, the production is quite low, only about 1000 ha in Slovakia, Hungary, and Italy. In the Mediterranean region amaranth is grown as a leafy vegetable (D'Amico et al., 2017). There was much greater cultivation in Russia, amounting to about 100,000 ha (Moudry et al., 1999).

In Africa, amaranth is mainly grown for its leaves as vegetable, in Tanzania, Benin, Togo, Sierra Leone, DR Congo and Kenya (Mwambo et al., 2015). In Tanzania, amaranth area represents 5.3% of the area dedicated to vegetables, and amaranth ranked 1st in the top 5 vegetables grown in North-East Tanzania (NBS, 2012; Keller, 2004).

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Forage management 

Crop management

Foxtail amaranth (Amaranthus caudatus) is propagated by seed as a sole cropping or in intercropping systems (with maize, millet, bean or cassava). In Peru the sowing rate ranges from 8-18 kg/ha while, in Kenya, it is only 1-2 kg/ha. Prior chemical (sulfuric acid) or physical (sandpaper) scarification of seeds is recommended. In Peru, improved cultivars sown at  400,000–500,000 plants/ha gave the highest yields. Because of their small size, the seeds should not be sown deeper than 1-1.5 cm unless elevated temperature and dry conditions require deeper (down to 5 cm) sowing. The depth of sowing should be a trade-off between heat and drought resistance and emergence ability. The seedlings shoud be weeded at least once  during their first month of growth. After establishment, foxtail amaranth competes well with weeds. Hilling the plants provide weed control and reduces lodging (Agong, 2006).

The harvest should occur when theplant is still green to prevent grain shattering (Agong, 2006)

Seed harvest and seed yield

Seed yields of grain amaranths (Amaranthus spp.) are extremely variable ranging from 50 kg to 7200 kg/ha (Alemayehu et al., 2015). The highest yields were reported in South and Middle Americas (4600 - 7200 kg/ha), and the lowest, in Africa (50 - 2500 kg/ha)(Alemayehu et al., 2015). In North-western India, yields of foxtail amaranth are lower than those of Amaranthus hypochondriacus. Irrigation was reported to improve foxtail amaranth grain yield by 122% (from 900 to 2000 kg/ha) (Alemayehu et al., 2015).

Forage harvest and forage yield

After harvest and threshing of the grain, the stover of foxtail amaranth can be used as a source of nutritive fodder for livestock in the Andean area (with higher nutritive value than other crop residues found in this area.

Foxtail amaranth could be a potential source of forage as it produces larger amount of biomass in comparison to other high protein yielding forages in the tropics (NRC, 1989). In Central Yakutia (Russia), annual green biomass yield was 28.1t/ha, and DM yield was 6,44 t/ha (Maksimova, 2020).

After the grain is threshed, the crop residue (stover) can be used as a source of fodder for cattle. Research in Peru demonstrated that it has much better nutritional value than the residues of other Andean crops. Andean farmers traditionally maintain their livestock on foxtail amaranth crop residue during the dry season, when forage is limited. It also has potential as a forage crop. It can rapidly produce a large amount of biomass with a high protein content, in tropical areas where high-protein forages yield poorly (NRC, 1989).

Environmental impact 

Climate change friendly species

Amaranths are very interesting in challenging growing conditions, especially in respect of the consequences of climate change (Alemayehu et al., 2015).

Soil cover and soil remediation

In China, amaranths make valuable vegetative cover in mountainous regions with low soil fertility (Brenner et al., 2000). Foxtail amaranth might be cultivated and used as a hyperaccumulator in the uptake of Cd from the Cd contaminated soils (Cay, 2016).

Nutritional aspects
Potential constraints 

Toxicity

Foxtail amaranth grain was found to be toxic to pigs (see pig section) (Takken et al., 1985).

Ruminants 

Foxtail amaranth can also be used as livestock feed. In turkey it was reported that the straw of amaranthus caudatus cv. Helios had the highest crude protein  among 3 amaranths. Moreover the straw had better nutritive value when the amaranths were grown under dry conditons (Keskin et al., 2020).

According to the mean values reported from an experiment in Thailand with 4 species of Amaranthus spp. it was show that after 75 days of growth the average value of DM for leaf and stems were 16.4 and 15.5 while the crop residue of amaranths was about 82.3 in DM. The crude protein was respectively 12.4; 3.2 and 7.2 for leaf, stem and crop residue while the NDF was 34.1; 63.9 and 62.4 and the ADF was 17.4; 48.5 and 49.1. Cows could be fed on 40% concentrate + amaranth residue ad libitum + 18-20 kg fresh grass daily during 60 days with no DM intake or milk yield reductions. Adding amaranth to the ration increased milk fat to 4.6% (Chairatanayuth, 1985

In China, amaranth has been used as forage for several types of livestock (Brenner et al., 2000).

Pigs 

Foxtail amaranth grain offered to pigs first resulted in feed refusal and progressive acceptance as the animals became used to the feed but the acceptance took more time when the level of foxtail amaranth was high in the diet. Feeding foxtail amaranth caused sudden death within one month in 10 pigs after 7 weeks of foxtail amaranth provision. Nine of these died pigs had mild to severa myocardial degerneration. Heat treatment (steam press pelleting) could not alleviate the problem (Takken et al., 1985). 

Poultry 

Foxtail amaranth grain

The seeds of foxtail amaranth (Amaranthus caudatus) could be fed at 5 or 10 % inclusion (dietary level) to 90 day-old broiler females during 32 days as a supplement in diets containing linseed oil (Longato et al., 2017).

Foxtail amaranth grain inclusion decreased growth performance significantly while it improved serum antioxydant power and decreased lipid oxidation at 5% and 10% inclusion. Foxtail amaranth in broilers diet decreased cholesterom and triglycerides levels but did not change meat fatty acid profiles nor meat quality (Longato et al., 2017).

 

Rabbits 

Forage

Many studies were conducted on the use of Amaranthus spp. forages in animal feeding (Peiretti, 2018; Manyelo et al., 2020). However, no information seems available in the international literature on the specific use of foxtail amaranth (Amaranthus caudatus) forage in rabbit feeding (as of February 2021). Nevertheless, foxtail amaranth residual pulp obtained after leaf fractionation can replace maize in rabbit feeding at 10% even 20% without significant alteration of feed intake or growth rate (Omole et al., 1979). In addition, ethanol extract of foxtail amaranth leaves administered to cholesterol fed rabbits (150 mg /kg body weight daily during 60 days) decreased the most important risk factors (the serum lipoproteins, apoB and Ox-LDL) of cardiovascular diseases and inflammatory factors prevented atherosclerosis and was more effective than lovastatin (Kabiri et al., 2010). If foxtail amaranth were to be used as safe forage in rabbit feeding the vegetative stage of the plant should be taken into account since for example the protein content of dry matter can vary from 24% (early vegetative) down to 7% (early flowering) within 36 days (Peiretti et al., 2018).

Grain

As for the use of the forage, information on the use Amaranthus caudatus grain in rabbit feeding seems very scarce in the international literature. However, for hyperchlesterolemic rabbits, the introduction of extrududed A. caudatus grain during 21 days, reduces LDL and cholesterol levels in the serum, without modification of the growth rate(Plate et al., 2002). It is noticeable that the raw or extruded grains are very rich in sulphur amino acids (twice requirement of rabbit), are relatively rich in lysine (1.3 times rabbit’s requirement) contrary to true–cereals (60 to 75% of rabbits ’requirement) but deficient in threonine (about 90% of requirement) (Chavez-Jauregui et al., 2000).

Fish 

Rainbow trout (Onchorynchus mykiss)

In an experiment aiming at assessing apparent digestibility coefficient of different Peruvian feedstuffs (jumbo squid (Dosidicus gigas), kañiwa (Chenopodium pallidicaule Aellen), kiwicha (Amaranthus caudatus L), quinoa (Chenopodium quinoa Willd), beans (Phaseolus vulgaris L.), and sacha inchi (Plukenetia volubilis L)), Junvenile rainbow trouts could be fed on commercial diets including 30% of these alternative feedstuffs during 25 days. Apparent digestibility coefficient of DM, OM, CP were respectively 58.9%, 63.1%; 89.1% for foxtail amaranth meal and digestible energy was 2.74 Mcal/kg. Foxtail amaranth meal ranked 4th among the 6 feedstuffs assessed and was thus not considered as reliable potential feed for juvenile rainbow trout (Ortiz-Chura et al., 2018)

Shrimps

In an attempt to replace fishmeal in Litopenaeus vannamei diets,  amaranth meal and quinoa meal were included at increasing levels (15; 25; 35; and  45% replacement of fishmeal). Amaranth meal inclusion resulted in lower growth rates in shrimps while it had better digestibility of DM and CP at 15% inclusion. Growth rates of shrimps fed on quinoa were always better than those with amaranth meal and could replace up to 45% fishmeal while amaranth meal could only replace 15% fishmeal with impaired growth performance (Molina-Poveda et al., 2015).

 

Nutritional tables
Tables of chemical composition and nutritional value 
References
References 
Datasheet citation 

DATASHEET UNDER CONSTRUCTION. DO NOT QUOTE. https://www.feedipedia.org/node/573 Last updated on April 8, 2021, 11:42