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Dwarf koa (Desmanthus virgatus)

Datasheet

Description
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Common names 

Dwarf koa, desmanthus, bundle flower [English]; bilil, brusca prieta, frijolillo, ground tamarind, guajillo [Spanish]; koa nain, petit acacia, petit cassie, petit mimosa [French]; guashillo, huarangillo, langalet, virgate mimosa [Hawaï]; 合欢草 [Chinese]

Synonyms 

Acacia angustisiliqua (Lam.) Desf., Acacia virgata (L.) Gaertn., Acuan depressa (Willd.) Kuntze, Acuan depressum (Willd.) Kuntze, Acuan texanum Britton & Rose, Acuan tracyi Britton & Rose, Acuan virgatum (L.) Medik., Desmanthus depressus Willd., Desmanthus leptophyllus DC., Desmanthus pernambucensis (L.) Thell., Desmanthus pratorum Macfad., Desmanthus strictus DC., Desmanthus tenellus DC., Desmanthus virgatus (L.) Willd. var. depressus (Willd.) B.L.Turner, Mimosa angustisiliqua Lam., Mimosa depressa (Willd.) Poir., Mimosa pernambucensis L., Mimosa virgata L.

Desmanthus virgatus, Desmanthus pubescens, Desmanthus pernambucanus, Desmanthus glandulosus and Desmanthus leptophyllus were not considered to be different species until 1993 and many authors continued to refer to all species as Desmanthus virgatus in the literature until the late 1990s (Cook et al., 2005).

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Related feed(s) 
Description 

Dwarf koa (Desmanthus virgatus (L.) Willd.) is a highly variable perennial legume. Morphology and habit range from a prostrate herbaceous plant, less than 50 cm high, to an erect or decumbent woody shrub, up to 2.5-3 m high (Gutteridge et al., 1994). It has a deep taproot and is strongly branched from the base. The stems are slender, pithy in the center, angular, green turning brown. The leaves are 2-8 cm long, compound, bipinnate, bearing 10-25 pairs of linear-oblong, 4-12 mm long x 1.5-3 mm broad leaflets. The inflorescence bears 9-11 whitish mimosoid flowers. The fruits are linear, dehiscent, 5.5-8.5 cm long pods. They contain 11-26 reddish-brown or golden-brown U-shaped seeds. Dwarf koa is morphologically very similar to Leucaena leucocephala (also called koa haole) but it is smaller and bears smaller leaflets, hence the name "dwarf koa" (FAO, 2010; Cook et al., 2005).

Dwarf koa is primarily used as forage. It is highly palatable to ruminants and may be grazed or fed fresh in cut-and-carry systems (FAO, 2010). It is one of the legumes most tolerant to grazing and withstands regular cutting (US Forest Service, 2010; Cook et al., 2005). It also helps to control soil erosion, provides green manure and adds N to the soil (Ecocrop, 2010).

Distribution 

Dwarf koa originated from tropical and subtropical Americas. It is widespread in Texas and Florida in the USA, in Veracruz and Chiapas in Mexico, in the Caribbean and throughout Central and South America (Cook et al., 2005). It is naturalized in African dry lands (Senegal, Zambia, South-Africa), in the Pacific Islands (New Caledonia, Hawaii) and Indonesia (FAO, 2010). It was introduced in India and Australia (Pengelly et al., 1992). Dwarf koa is mainly found in coastal thickets, roadsides and heavily disturbed areas, from sea-level to an altitude of 2000 m, but most commonly below 500 m (Ecocrop, 2010; Cook et al., 2005).

Dwarf koa is very adaptive and can grow under a wide range of temperatures (including frost conditions) and rainfall conditions (from 250 to 2000 mm) (Cook et al., 2005; Pengelly et al., 1992). Dwarf koa prefers neutral to alkaline clay or clay-loam soils but is also known to do better than Leucaena on acid infertile soils (Gutteridge et al., 1994; Pengelly et al., 1992). It is also tolerant of sodic soils (Cook et al., 2005). Dwarf koa is a very drought-tolerant legume. It withstands frost and fire (which may suppress buried seed dormancy) since it can regrow from the crown. Dwarf koa tolerates severe competition from grasses and herbs but disappears when overtopped by trees since it does not withstand shaded conditions (Francis, 2003; Cook et al., 2005).

Forage management 

Yields of dwarf koa range from 7.6 t DM/ha in the humid tropics (2000 mm rainfall) to 2-2.4 t DM/ha in low rainfall (600-750 mm) areas in Northern Australia (Cook et al., 2005). In a comparative study with various fodder legume trees and shrubs in Ghana, Desmanthus virgatus was among the low-yielding species and much less productive than Gliricidia sepiumCalliandra calothyrsus or Cajanus cajan (Barnes, 1998).

Desmanthus virgatus withstands regular cutting, and plantations can be cut for feed 4 (Cook et al., 2005) or 6 times a year (Radhakrishnan et al., 2007). In drought-prone areas, dwarf koa is one of the most resistant legumes and was able to persist under grazing over a 14 year period (Cook et al., 2005).

Desmanthus virgatus was found less suitable than Leucaena leucocephala (lower protein and in vitro OMD) for grass-legume forage production in alley cropping in the Caribbean (Adjei, 1995).

The contribution of Desmanthus virgatus to pasture yield is higher in harsh environments than in more favourable ones, so that it is relatively more valuable on soils of moderate fertility in environments with a marked dry season (Cook et al., 2005).

Environmental impact 

N-fixing legume

Dwarf koa, provided it is inoculated with adequate rhizobium strains, is a good N-fixing legume. In places where it is not native (Australia), dwarf koa should be inoculated before sowing (Brandon et al., 1998).

Erosion control

Used in alley cropping, dwarf koa helps controlling soil erosion on steep slopes in the Philippines (US Forest Service, 2010).

Other services

Dwarf koa is an efficient nursery-stage host for highly priced sandalwood (Ecocrop, 2010).

Weed potential

Because of it vigorous growth, dwarf koa may become a minor weed in disturbed areas (Cook et al., 2005) and a serious weed in sugar cane fields (US Forest Service, 2010).

Nutritional aspects
Nutritional attributes 

Like many other tropical legume plants, dwarf koa has a fairly high protein content, typically in the 15-20% DM range, and the leaves have a higher protein content than the stems (22-28% DM for the leaves vs. 7% for the stems) (Ly et al., 2001; Skerman et al., 1990; Radhakrishnan et al., 2007; Ramirez et al., 2000). Lower protein values (8.9% DM) and much higher fibre values (58.3-73.5% DM) have been reported for Desmanthus virgatus hay (Rangel et al., 2009). Compared to 15 other shrub species from northeastern Mexico, Desmanthus virgatus had an average crude protein content (17.8% DM vs. 25.2% DM for Leucaena leucocephala) and a low NDF (25.9% DM). It was moderately rich in AD lignin (10.6% DM), and high in condensed tanins (8.3% DM) and insoluble ash (2.0% DM) (Ramirez et al., 2000; Ramirez et al., 2001). Empty pods contain much less protein (9% DM) than the whole plant or the leaves (Keoghan, 1980).

Unlike LeucaenaDesmanthus virgatus does not contain mimosine and therefore can be fed safely to non-ruminants (Gutteridge et al., 1994).

Potential constraints 

Dwarf koa, unlike Leucaena leucocephala, does not contain mimosine or other toxicants (Gutteridge et al., 1994). However, it contains significant amounts of tannins (Adjei, 1995; Ramirez et al., 2001).

Ruminants 

Dwarf koa is non-toxic to ruminants and is used for both fodder and grazing (Göhl, 1982). The high condensed tannins content of Desmanthus species can prevent bloat (Cook et al., 2005).

Palatability

Desmanthus virgatus is palatable to ruminants. It has been observed to be less palatable than leucaena but more readily eaten than Stylosanthes scabra. Its relative palatability depends on the variety or accession (Cook et al., 2005).

Nutritive and feeding values

In vivo DM and N digestibility in cattle fed Desmanthus virgatus leaf meal has been reported to be low: 48 and 44%, respectively (Göhl, 1982), though a higher DM digestibility has also been reported (55%) (Kharat et al., 1980). In sacco effective degradability of NDF was also low (36%) (Ramirez et al., 2000).

Sheep

There is little published information on the use of Desmanthus virgatus in ruminants. A DM intake of 5% of body weight was reported for Desmanthus virgatus fodder in sheep, and the authors concluded that it was a potential leguminous fodder source for small ruminants (Radhakrishnan et al., 2007). In Australia, preliminary research suggests that sown Desmanthus virgatus could fulfill the role of Stylosanthes species in the Mitchell grass (Astrebla spp.) bioregion of Western Queensland: 200 g/d of dwarf koa hay added to 600 g/d of Astrebla hay had beneficial effects on wool growth, DM intake, ME intake, N intake and weight loss. The relatively high protein content and the sulphur content (0.36% DM) could be beneficial to wool production (Rangel et al., 2009).

Pigs 

There is a paucity of literature on the use of dwarf koa in pig feeding. While the absence of mimosine should make Desmanthus virgatus safer than Leucaena for monogastric animals, one attempt to feed pigs with sun-dried leaves (17% in the diet DM) reported extremely low OM, NDF and N digestibilities (37, 30 and 2% respectively) and the authors concluded that dwarf koa leaf meal was unsuitable as an alternative protein source for pigs, unless methods to increase its nutritive value were developed (Ly et al., 2001).

Poultry 

The nutritional value of dwarf koa leaf meal in poultry is low, as reported for most leaf meals (D'Mello, 1995). An ME value of 5.6 MJ/kg was reported, but when taking this value into account for feed formulation, performance of layers was maintained up to 6% incorporation in diets while enhancing egg yolk coloration (Buakeeree, 2002; Suksombat et al., 2006).

The use of seeds from a related species (Desmanthus illinoensis) in broilers resulted in depressed performance, even at 5% inclusion level, and is therefore not advisable (Jacob, 2007).

Rabbits 

Dwarf koa may be fed to rabbits, alone or in combination with pelleted feed or commercial mash, without altering their health parameters (Jegatheesan et al., 2006). Dwarf koa resulted in greater weight gains than agati (Sesbania grandiflora), Leucaena (Leucaena leucocephala) and Tridax daisy (Tridax procumbens) when it supplemented a concentrate feed (Singh et al., 2007).

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 35.2 32.0 38.3 2
Crude protein % DM 15.8 3.5 11.5 22.8 9
Crude fibre % DM 34.0 11.0 17.6 41.1 4
NDF % DM 46.7 32.5 60.9 2
ADF % DM 37.0 20.5 53.4 2
Lignin % DM 13.1 7.0 19.3 2
Ether extract % DM 3.0 0.8 2.4 4.2 4
Ash % DM 6.4 1.4 4.9 8.9 9
Gross energy MJ/kg DM 19.3 *
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 16.5 11.8 2.6 40.5 8
Phosphorus g/kg DM 3.3 1.6 2.1 5.2 3
Potassium g/kg DM 19.9 17.4 22.3 2
Sodium g/kg DM 0.8 1
Magnesium g/kg DM 8.5 5.0 12.0 2
 
Secondary metabolites Unit Avg SD Min Max Nb
Tannins (eq. tannic acid) g/kg DM 73.5 1
Tannins, condensed (eq. catechin) g/kg DM 0.0 1
 
Ruminant nutritive values Unit Avg SD Min Max Nb
OM digestibility, Ruminant % 61.2 *
Energy digestibility, ruminants % 58.5 *
DE ruminants MJ/kg DM 11.3 *
ME ruminants MJ/kg DM 9.0 *
Nitrogen digestibility, ruminants % 44.0 1

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

References

Barnes, 1998; CIRAD, 1991; Nasrullah et al., 2003; Work, 1938

Last updated on 24/10/2012 00:44:08

Main analysis Unit Avg SD Min Max Nb
Dry matter % as fed 93.2 0.8 92.3 94.6 6
Crude protein % DM 28.0 4.0 20.6 31.3 6
Ether extract % DM 1.9 0.3 1.6 2.4 6
Ash % DM 3.8 0.3 3.5 4.4 6
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 2.5 0.4 1.9 2.9 6
Phosphorus g/kg DM 4.3 0.7 3.6 5.2 6
Potassium g/kg DM 9.0 0.4 8.4 9.5 6
Sodium g/kg DM 0.0 0.0 0.0 0.1 6
Magnesium g/kg DM 2.7 0.2 2.4 3.0 6
Manganese mg/kg DM 66 18 47 89 6
Zinc mg/kg DM 50 5 47 61 6
Copper mg/kg DM 13 4 8 18 6
Iron mg/kg DM 87 26 67 135 6

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

References

Schlink et al., 1993

Last updated on 24/10/2012 00:45:33

References
References 
Datasheet citation 

Heuzé V., Tran G., Sauvant D., Bastianelli D., 2015. Dwarf koa (Desmanthus virgatus). Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. http://www.feedipedia.org/node/307 Last updated on May 11, 2015, 14:31

English correction by Tim Smith (Animal Science consultant) and Hélène Thiollet (AFZ)