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Bengal indigo (Indigofera arrecta)

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 

Bengal indigo, Java indigo, Natal indigo [English], añil de Java [Spanish], indigotier, indigotier chessé [French]

Taxonomic information 

Indigofera arrecta, Indigofera suffruticosa and Indigofera tinctoria are closely related, and intermediate specimens (possibly of hybrid origin) have been found (Orwa et al., 2009).

Feed categories 
Description 

Bengal indigo is a multipurpose, stout shrub that is often cultivated as an annual. It has long been a major source of the famous indigo (deep blue colour) dye, now replaced by synthetic dyes. Young leaves are sometimes eaten and the plant is a useful cover crop, contour hedge plantations and green manure in plantation crops such as rice, cotton, hevea, tea or coffee. 

Morphology

Bengal indigo (Indigofera arrecta Hochst. ex A. Rich.) is an erect, many-branched, woody, large shrub up to 3 m tall, perennial but often cultivated as an annual. The leaves are alternate, pinnately compound. Each rachilla bears 12-17 leaflets that are obovate or elliptical and about 1-1.5 cm long x 0.7 cm broad. The inflorescence is an axillary raceme bearing.  The pods are straight, 2-2.5 cm long. They contain 6-8 seeds ( Orwa et al., 2009; Lemmens et al., 2006). 

Uses

Bengal indigo was the major source of the famous indigo dye. The leaves and twigs contain colourless precursors of the deep blue dye. They had to be soaked in water added with lime, and to undergo fermentation and enzymatic hydrolysis to yield a blue slurry which was then dried and cut into cubes. The cubes could further be put in water to dye textiles (Fern, 2021). The residues of indigo extraction could be used as manure (Lemmens et al., 2006). Bengal indigo has been used as a browse shrub and its foliage has been reported to be as palatable as leucaena to sheep (Kaitho et al., 1996; Göhl, 1982). Young leaves could be cooked and eaten (Fern, 2021; Lemmens et al., 2006). There are also many ethnomedicinal uses of Bengal indigo (Orwa et al., 2009).

Distribution 

Bengal indigo (Indigofera arrecta) is native to Eastern and Southern Africa. It is found almost throughout tropical Africa, and also in Northern and Eastern South Africa, Swaziland and Southern Arabia. It has been introduced for indigo production in many other areas where it became naturalized. It is widely planted in India and south-eastern Asia (Lemmens et al., 2006). It was introduced to Laos, Vietnam, the Philippines (Luzon) and Indonesia (Sumatra, Java, Sumba, Flores) (Orwa et al., 2009).

Bengal indigo occurs in open deciduous forest, evergreen bushland, often in forest margins, and secondary regrowth. It is found from 200 to 2700 m altitude, in places where annual rainfall is 400-1800 mm. Bengal indigo is deeply rooted and is tolerant to droughts. Once well established, bengal indigo withstands waterlogging/flooding conditions for up to 2 months. It is also tolerant of salinity (Hassen et al., 2007).

Bengal indigo is a full sunlight species. When it is intended for use as a cover crop, Bengal indigo should only be grown in gardens or plantations with little or no shade (Lemmens et al., 2006).

 

Forage management 

Yield

Bengal indigo is a relatively high yielding browse shrub. In South Africa, it yielded 3 and 16 t DM/ha during 2 consecutive years, encompassing 1.2 and 3.2 t DM for leaf /ha (Hassen, 2006).

Management

Propagation is done by seed. Because of their hardcoat, the seeds should be scarified by soaking in water or with sulphuric acid before being broadcasted directly in the field (3 seeds/hole) orr on a well-prepared and wet seedbed. After sowing, the shrub normally requires little attention. Weeding is done when needed. When it is managed as a cover crop, Bengal indigo is slashed at regular intervals (Lemmens et al., 2006). It is generally browsed at the end of the dry season, when young subsidiary shoots are more palatable (Orwa et al., 2009).

Environmental impact 

Cover crop, soil improver, erosion control

Indigofera arrecta is a N-fixing legume and a soil improver. It is also used as a cover crop and for green manure (Orwa et al., 2009). It has been used on slopes to prevent erosion (Akbarillah et al., 2010).

Nutritional aspects
Nutritional attributes 

Leaves and stems

Leaves of I. arrecta have a high CP concentration (180-260 g CP/kg DM), as those of other Indigofera species in South Africa (Hassen et al., 2008; Hassen et al., 2007; Agishi, 1983). Their NDF (295 g/kg DM), ADF (196 g/kg DM) and ADL (60 g/kg DM) concentrations are low when compared to leaves of other tree species of Ethiopia (Kaitho et al., 1998).
When leaves are mixed with fine stem (< 3 mm), considered as edible forage material, CP concentration is lower (150-180 g/kg DM) and NDF concentration is greater (330-590 g/kg DM) (Tjelele, 2006; Hassen, 2006). The difference of chemical composition between leaves alone and leaves + stem depend on the season and of the leaves proportion. The CP concentration and IVOMD are greater, and NDF concentration is lower, in spring than in autumn (Hassen et al., 2007).

Leaves ash (60 to 122 g/kg DM), Ca (10 to 38 g/kg DM), P (1.9 to 3.5 g/kg DM), Mg (2 to 6 g/kg DM) concentrations, as well as Cu, Zn and Mn concentrations, are similar to that of other Indigofera species (Hassen et al., 2008; Hassen et al., 2007Agishi, 1983).

Seeds

Depending on pre-treatment technique, the seeds of Bengal indigo contain, per kg DM, 160 to 280 g of CP, 7.0 to 8.8 g of crude fat, 420 to 545 g of carbohydrates, 131 to 321 g cellulose, and 75 to 263 g lignin (Ahmadu et al., 2017). The main effect of treatment is to reduce lignin, hemicellulose and cellulose concentrations, as well as antinutritional factors (tannin, phytate, alkaloid, saponin, oxalate mainly)
(Ahmadu et al., 2017).

Potential constraints 

Antinutritional factors

The leaves of Bengal indigo (Indigofera arrecta) contains indospicine, an antinutritional compound which may cause hepato-toxicity in grazing cattle and sheep (Fletcher et al., 2015; Hassen et al., 2008), at a concentration ranging from 26 to 289 mg/kg DM. The toxicity level of indospicine is not clear, but its concentration may rise to 2000 mg/kg DM in some Indigofera sp. accessions (Fletcher et al., 2015).

Bengal indigo leaves have low condensed tannins (3 g/kg DM) and medium total phenols (30 g/kg DM) compared to others tree foliages (Kaitho et al., 1998).

Ruminants 

Not very palatable during the rainy season, but well browsed toward the end of the dry season, when the young subsidiary shoots are also readily eaten.

Thanks to their high protein content, bengal indigo leaves could be considered as potential protein supplements in low quality diets for cattle and sheep rations (Hassen et al., 2008; Hassen et al., 2007; Agishi, 1983).

Degradability, digestibility

The effective degradability of DM in leaves was about 69% (Kaitho et al., 1998) and the IVOMD was close to 70% (Hassen et al., 2008). The in vitro digestibility (IVOMD) of a mixture of leaves and edible fine stems was reported to be lower (53%) (Hassen, 2006).

Cattle

No information could be found (as of 2021).

Sheep

When offered to 1-year old wethers (live weight 19 kg) as a supplement to 0.4 kg of straw, fresh foliage of I. arrecta are fed at around 105 g DM/d, less than Leucaena spp. (120-140 g DM/d), but close to the intake of Sesbania sesban, known for its high feeding value (Kaitho et al., 1996). It has been classified in the most palatable species (cluster 1) when compared to 40 other tree species in Ethiopia (Kaitho et al., 1996).

In adult Merino wethers (62 kg), voluntary intake (52 g/kg LW 0.75 /d), apparent DM digestibility (63%), apparent NDF digestibility (52%) of a mixture of leaves and fine stem (< 3 mm) were similar than that recorded with Leucanea leucocephala, and lower that that recorded on lucerne (Hassen, 2006).

Goat

In growing goats, voluntary intake of Bengal indigo fed as the sole forage and supplemented with concentrate is greater when fed as fresh than ensiled (Ginting et al., 2012). In that study, it is recommended to include I. arrecta in complete diets at a maximum of 65% of the diet to avoid too low ADG.

Rabbits 

Information on the potential use of  Bengal indigo (Indigofera arrecta) in rabbit feeding is very scarce in the international literature (March 2021). However, a large use of Bengal indigo leaves (25% crude protein in DM) was proposed some years ago for a rabbit development program in Mozambique (Gaspari, 1979).

Nutritional tables
Tables of chemical composition and nutritional value 

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

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).

Main analysis Unit Avg SD Min Max Nb
Dry matter % as fed 74.7 1
Crude protein % DM 27.4 5.0 23.1 32.8 3
Crude fibre % DM 19.6 13.7 25.5 2
NDF % DM 29.5 1
ADF % DM 19.6 1
Lignin % DM 6.0 1
Ether extract % DM 2.2 1
Ash % DM 9.3 2.7 6.8 12.2 3
Gross energy MJ/kg DM 18.7 *
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 12.7 11.9 13.6 2
Phosphorus g/kg DM 3.3 3.2 3.5 2
Potassium g/kg DM 16.2 1
Sodium g/kg DM 0.0 1
Magnesium g/kg DM 1.9 1
 
Secondary metabolites Unit Avg SD Min Max Nb
Tannins, condensed (eq. catechin) g/kg DM 3.0 1
 
Ruminant nutritive values Unit Avg SD Min Max Nb
OM digestibility, Ruminant % 75.7 *
Energy digestibility, ruminants % 72.4 *
DE ruminants MJ/kg DM 13.5 *
ME ruminants MJ/kg DM 10.6 *

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

References

Dougall et al., 1966; Kaitho et al., 1997; Pozy et al., 1996

Last updated on 24/10/2012 00:44:22

References
References 
Datasheet citation 

DATASHEET UNDER CONSTRUCTION. DO NOT QUOTE. https://www.feedipedia.org/node/291 Last updated on September 8, 2021, 10:02