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Feedipedia

African couch grass (Digitaria abyssinica)

Datasheet

Description
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Common names 

African couch grass, African couchgrass, African couch, Dunn's finger grass, Abyssinian finger grass [English]

Synonyms 

Panicum muticum Hochst., Digitaria scalarum (Schweinf.) Chiov., Digitaria vestita Fig. & DeNot., Digitaria abyssinica var. scalarum (Schweinf.) Stapf, Digitaria eichingeri Mez, Digitaria hackelii (Pilg.) Stapf, Digitaria merkeri Mez, Digitaria mutica Rendle, Digitaria somaliensis Chiov., Digitaria tangaensis Henr., Panicum abyssinicum A. Rich., Panicum hackelii Pilg., Panicum kafuroense K. Schum., Panicum scalarum Schweinf.

Related feed(s) 
Description 

The African couch grass (Digitaria abyssinica (Hochst. ex A. Rich.) Stapf) is a tropical perennial grass. It can be erect or decumbent, trailing or creeping at the base (CABI, 2012; Quattrocchi, 2006). It has long, slender and wiry rhizomes that form a dense mat beneath the soil surface and can go deeper than 1 m. The rhizome may twine around the roots of other crops and smother them (CABI, 2012). The culms are slender, erect, up to 50-100 cm high (FAO, 2012). The leaves are linear, flat, 2-12 cm long, 3-5 mm (7-8 mm) wide, with a bluish-green colour (Quattrocchi, 2006). The inflorescence is a panicle of 2 to 25 racemes, borne along a 2-11 cm long central axis. Spikelets are paired and glabrous (FAO, 2012; Clayton et al., 2006). The fruit is an ellipsoid seed, variable in colour (FAO, 2012).

In the vegetative stage, Digitaria abyssinica can be confused with Bermuda grass (Cynodon dactylon), but Digitaria abyssinica has only 1 leaf per node instead of 2-3 for Bermuda grass (CABI, 2012). Digitaria abyssinica is one of the most noxious weeds in crops, plantations and orchards (FAO, 2012). It is palatable to cattle and can be used as a low quality pasture (CABI, 2012; FAO, 2012). It is valued as a cover and ley crop (see Environmental impact below) (FAO, 2012; Quattrocchi, 2006).

Distribution 

Digitaria abyssinica is native to tropical Africa. It spreads from Nigeria to Arabia, and southwards to South Africa (CABI, 2012). It is mainly found as an arable weed in highland grasslands of East Africa where it is usually grazed (Bogdan, 1977). It has also been recorded in Madagascar, India, Sri Lanka and the USA (Hawaii included) (CABI, 2012; US Forest Service, 2012). Digitaria abyssinica is common in humid areas, in moist shady places, roadsides, disturbed ground, mountains, along streams and riverbanks (Quattrocchi, 2006). It is found from sea level up to an altitude of 2900-3000 m, particularly in moister areas (rainfall higher than 500 mm). Digitaria abyssinica grows on a wide range of soils, including dry or muddy ones, but it does better on rich soils and sandy loams (FAO, 2012; CABI, 2012). It can grow on no-tillage soils and is common in natural grasslands in East Africa (CABI, 2012).

Forage management 

An early report in KwaZulu-Natal (South Africa) showed that Digitaria abyssinica responded positively to N fertilizer, doubling DM production per ha. It was believed that potential DM production could reach 4-7 t DM/ha/year depending on the application of N fertilizer (Deenik, 1938). A more recent study reported a yield of 36-44 t/ha of fresh matter (Richardson, 1967 cited by CABI, 2012).

Environmental impact 

Weed

Digitaria abyssinica is considered a noxious weed. It occurs in a wide range of annual or perennial crops (Murdoch et al., 2003; Skerman et al., 1990). In Ethiopia, it was judged as the main weed by 86% of farmers in the highlands (altitude higher than 1900 m). Due to their great depth, the rhizomes are extremely difficult to remove without chemicals (Baguma et al., 1995; Skerman et al., 1990). Mechanical tillage with animals may injure their shoulders due to too heavy traction. Tillage with tractors can expose rhizomes to desiccation on the soil surface, but can also spread the fragmented rhizomes (CABI, 2012).

Cover crop

Digitaria abyssinica may be helpful in soil binding. Its deep rhizomes help in linking soil elements thereby reducing erosion on sloping land (CABI, 2012). It has been planted on the slopes of the Cape Peninsula in South Africa to control erosion (Chippindall, 1955 cited by Skerman et al., 1990).

Nutritional aspects
Nutritional attributes 

Limited information is available on the composition of Digitaria abyssinica. The fresh grass has a relatively high crude protein content (15-17% DM) with relatively low levels of fibre (crude fibre 28-33% DM) and lignin (less than 5% DM). Two samples of Digitaria abyssinica hay were found to have a low protein content (Berhane et al., 2006; Murdoch et al., 2003; Dougall et al., 1960; Teklu et al., 2010; Feedipedia, 2013).

Ruminants 

Digitaria abyssinica has been more studied as a noxious weed than as a forage. Early reports noted that it was relished by cattle, but not very productive (Göhl, 1982). It may have a good nutritive value for ruminants with a high in vitro DM digestibility of 74% reported on fresh grass (17% protein) (Murdoch et al., 2003). However, a much lower in vitro DM digestibility value of 49% was found for poor quality hay (7% protein) (Teklu et al., 2010). In Ethiopian grazing systems, livestock owners considered Digitaria abyssinica to be less desirable than Bermuda grass (Cynodon dactylon) but as desirable as Cenchrus ciliaris (Teklu et al., 2010).

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
Crude protein % DM 15.6 1.2 14.6 17.0 4
Crude fibre % DM 28.3 0.6 27.7 29.0 3
NDF % DM 63.9 *
ADF % DM 33.5 *
Lignin % DM 3.9 *
Ether extract % DM 3.0 0.7 2.5 3.8 3
Ash % DM 9.1 0.3 8.8 9.5 4
Gross energy MJ/kg DM 18.5 *
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 4.0 3.5 4.5 2
Phosphorus g/kg DM 3.6 3.1 4.0 2
Potassium g/kg DM 25.7 21.7 29.8 2
Magnesium g/kg DM 3.9 3.3 4.4 2
Manganese mg/kg DM 146 1
Zinc mg/kg DM 67 1
Copper mg/kg DM 15 1
 
Ruminant nutritive values Unit Avg SD Min Max Nb
OM digestibility, Ruminant % 70.5 *
Energy digestibility, ruminants % 67.4 *
DE ruminants MJ/kg DM 12.5 *
ME ruminants MJ/kg DM 10.0 *

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

References

Berhane et al., 2006; CIRAD, 1991; Dougall et al., 1960

Last updated on 02/04/2013 14:50:21

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 96.0       1  
Crude protein % DM 7.8   7.3 8.3 2  
NDF % DM 70.4   70.4 79.2 2 *
ADF % DM 41.1   38.5 43.8 2  
Lignin % DM 5.6         *
Ash % DM 12.4   10.3 14.6 2  

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

References

Berhane et al., 2006; Teklu et al., 2010

Last updated on 02/04/2013 15:32:29

References
References 
Datasheet citation 

Heuzé V., Tran G., Delagarde R., 2016. African couch grass (Digitaria abyssinica). Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. http://www.feedipedia.org/node/455 Last updated on March 15, 2016, 13:39

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