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Sweet thorn (Acacia karroo)

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
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Common names 

Sweet thorn, cape gum, cape thorn tree, cockspur thorn, deo babool, karroo thorn, karrothorn, mimosa thorn, white-thorn [English], mimosa à longues épines, mimosa hérissé, mimosa odorant, cassie, piquants blancs [French]; Akazie, Süssdorn-, Akazie, Weissdorn [German]; acacia orrida, mimosa karroo [Italian]; Cape gum, cassie, doorn boom,doringboom, mookana,piquants blancs; soetdoring; umuNga [South Africa]; aromo de Sudáfrica [Spanish], سنط كارو [Arabic]; آکاکیا کارو 5 [Farsi]; kaludai, , kikar, mormati, pahari kikar, pahari kikar

Synonyms 

Acacia campbellii Arn., Acacia dekindtiana A. Chev., Acacia eburnea sensu auct., Acacia horrida sensu auct., Acacia inconflagrabilis Gerstner, Acacia karoo Hayne, Acacia minutifolia Ragup., Acacia natalitia E. Mey., Acacia pseudowightii Thoth., Acacia roxburghii Wight & Arn., Mimosa eburnea L. f.

Related feed(s) 
Description 

Sweet thorn (Acacia karroo) is a very variable and very thorny species that is widespread in Africa and grows to a height of 5-12 m. It is a multipurpose tree providing food, feed, commercial products and environmental services. Livestock and wild animals relish on sweet thorn foliage, pods and seeds that do not contain antinutritional factors.

Morphology

Sweet thorn is a very variable thorny evergreen or almost evergreen shrub that grows to a height of 2-20 (-25) m.  It has a rounded crown. The branches emerge rather low on the trunk. The bark is smooth and dark red on young branches becoming rough or fissured and blackish on the trunk and on old branches. The leaves are alternate, pedunculated, bipinnate, bearing 2-7 pairs of primary pinnae each bearing 5-15 (-27) pairs of leaflets. Very long (up to 17 cm), straight, and conspicuous white spines are borne at the base of the leaf-stalk. The leaflets are 4-7 mm long x 1-3 mm broad. The flower-heads are axillary borne on young shoots and grouped in pompons, they are deep or golden yellow in colour. The flowers are ball-shaped. The fruit is a 18 cm long dehiscent pod, green to brown when mature. It is flat and has a crescent shape, constricted between the seeds. Pods split open at maturity. The seeds are small, 5-8 mm x 3-5 mm long, oblong-elliptic in shape, olive green to brown in colour (CABI, 2018; Aubrey et al., 2002; USForest 

Uses

Sweet thorn is a multipurpose tree that can be used for food, feed and commercial products. The foliage and the pods are readily eaten by livestock and wild life they can be browsed of cut and are reported to be deprived of anti nutritional substances. The tree yields an edible gum similar to arabic gum and useful for candy production. The seeds can be roasted to make a coffee substitue. The flowers are attractive to bees and the long flowering period allows to produce pleasant honey from the nectar. Sweet thorn is also valuable source of fuelwood and charcoal. The timber is used to make posts and pens. The bark yields tannins used for dyeing leather to a reddish colour but also providing an unpleasant odour. The inner bark is used to make ropes . Sweet thorn also provides environmental services (see environmental impact) (Ecocrop, 2019; Fern, 2014; Orwa et al., 2009; Aubrey et al., 2002).

 

Environmental impact 

Pioneering species

Sweet thorn in a fast growing species that establishes readily in full sunlight and does not need shelter or protection from grass fires. The seed germination might even be promoted by fires. Sweet thorn is resistant to heavy grazing, to fire and to frost. Goats grazing has been suggested for bush encroachment alleviation (Dingaan et al., 2018)

Soil improver, erosion control and reclamation

A N-fixing tree, sweet thorn (Acacia karroo) improves soil N status. It also extracts water from deep underground thus being an indicator for underground water. The development of its canopy benefits to the neighbouring grass growing under its canopy  (Dingaan et al., 2018). The benefits for grass production is related to sweet thorn density: a few trees improved grass production but high density (>300 trees/ha) is detrimental (Stuart-Hill et al., 1987). Sweet thorn is repoted to stabilize sand dunes and disturbed areas (CABI, 2018).

Live fence

A very thorny species, sweet thorn can be used as a living hedge (CABI, 2018).

Bush encroachment and invasiveness

Sweet thorn (Acacia karroo) is a pioneering species prone to become responsible for bush encroachment in grasslands and farming land in South Africa. It may thus be detrimental to grass production because of the competition for soil moisture between grass and trees and it results in lower livestock carrying capacity of grassland. In the Molopo area of South Africa, sweet thorn encroachment would have reduced grass production by 30% (Dingaan et al., 2018).

In Australia sweet thorn as been referred to as a noxious weed, requiring notification and destruction in some areas like New South Wales, western Australia states and Queensland (Pier, 2014).

 

Nutritional aspects
Potential constraints 

No prussic acid in the leaves and thorns.

Ruminants 

The leaves and fruit seldom eaten by stock, probably because of the long thorns.

Pigs 

Feeding Acacia karroo leaf meal at low (10%) inclusion level in the diet of pigs depressed nutrient digestibility, increased endogenous protein secretion and increased the activity of liver enzymes but did not reduce growth rate and was therefore considered as a potentially feasible technology (Halimani et al., 2005; Halimani et al., 2007).

Rabbits 

Feeding a diet containing 4% of Acacia nilotica leaf meal to growing rabbits did not result in differences in intake and digestibility. It was concluded that the amount of tannins in the diet was not high enough to have negative effects and that an inclusion rate of 4% was ideal for supplementation (Mashamaite et al., 2009).

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 91.3 1.1 90.0 92.0 3
Crude protein % DM 12.3 1.6 10.6 13.6 3
Crude fibre % DM 14.3 11.9 16.7 2
NDF % DM 42.8 29.7 55.9 2
ADF % DM 33.9 21.4 46.5 2
Lignin % DM 12.4 1
Ash % DM 11.0 6.8 15.3 2
Gross energy MJ/kg DM 21.3 1
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 27.0 1
Phosphorus g/kg DM 0.8 1
 
Secondary metabolites Unit Avg SD Min Max Nb
Tannins, condensed (eq. catechin) g/kg DM 4.0 1
 
Ruminant nutritive values Unit Avg SD Min Max Nb
OM digestibility, Ruminant % 81.1 *
Energy digestibility, ruminants % 77.5 *
DE ruminants MJ/kg DM 16.5 *
ME ruminants MJ/kg DM 13.6 *

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

References

Groenewald et al., 1967; Halimani et al., 2005; Mokoboki et al., 2011

Last updated on 24/10/2012 00:45:13

References
Datasheet citation 

DATASHEET UNDER CONSTRUCTION. DO NOT QUOTE. https://www.feedipedia.org/node/349 Last updated on September 20, 2019, 11:37