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Shittimwood (Acacia seyal)

Datasheet

Description
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Common names 
Shittim, shittimwood, red acacia, shittah tree, thirty thorn, whistling tree [English]
Synonyms 

Acacia fistula Schweinf., Acacia flava (Forssk.) Schweinf. var. seyal (Delile) Roberty, Acacia stenocarpa A. Rich.

Related feed(s) 
Description 

Shittimwood (Acacia seyal Del.) is a deciduous, prickly, small to medium sized shrub or tree. It reaches a height of 17 m after 8-10 years (Ecocrop, 2011; Orwa et al., 2009). The trunk is 20-60 cm in diameter, covered by a rust-coloured powdery bark. Shittimwood has a thin, top-flattened crown, similar to that of Acacia tortilis (Orwa et al., 2009). It may be sparsely branched and the branches are horizontal or ascending (Duke, 1983; NAS, 1980). Sharp straight spines occur on the branches and smaller, curved thorns are present near the tips of the branches (Orwa et al., 2009). The epidermis of twigs becomes reddish and shed annually (eFloras, 2010; Duke, 1983). The leaves are dark green, bipinnate with 3-7 pinnae which bear 11-20 pairs of leaflets. The leaflets are 3-8 mm long x 0.75-1 mm wide (Orwa et al., 2009). Shittimwood bears clusters of bright yellow, fragrant-spicy scented or sweet smelling flowers that grow short lateral shoots on the current season (Orwa et al., 2009; NAS, 1980). Shittimwood fruits are 6-10 seeded curved pods, 7-20 cm long, 0.5-0.9 cm broad and contain elliptic seeds (Orwa et al., 2009; Duke, 1983).

Shittimwood is a multipurpose tree. It provides valuable dense firewood that burns rather quickly, producing a fragrant smoke over which women perfume themselves (Orwa et al., 2009). Shittimwood also provides charcoal, timber for craft work and yields a gum that can be used as a substitute to gum-arabic (Ecocrop, 2011). Due to its spines, shittimwood is often used to make fences (Orwa et al., 2009).

Leaves, pods and flowers of shittimwood are a major source of early dry-season fodder that can be browsed or cut (Ecocrop, 2011; NAS, 1980). Pods and leaves are relished by ruminants. Shittimwood is considered the best fodder tree for Sahelian savannas where it grows in quantity. Herders drive their livestock to where shittimwood is common and/or they lop off branches for them. Lopping is sometimes too severe and may hamper shittimwood regrowth when over a third of the crown is removed (Le Houérou, 1980). Pruning of small branches gives a better forage yield than lopping of large branches (Orwa et al., 2009). Pods may be sold for fattening sheep (Duke, 1983; NAS, 1980). During the dry season, branches should be beaten in order to detach pods and leaves without damaging the buds rather than lopping the branches (Orwa et al., 2009).

Distribution 

Shittimwood is indigenous to the Sahelian zone from Senegal to Sudan (Ecocrop, 2011). It is a gregarious tree that grows in woodlands, wooded grasslands, within subtropical and tropical deserts, and very dry forest areas. Shittimwood is usually found near river beds, at lowland sites and near waterholes or seasonally flooded black cotton soils. Large herbivores may play an important role in seed dispersal (Razanamandranto et al., 2004). Shittimwood can be found up to an altitude of 2100 m, but is most common in lowlands (Ecocrop, 2011; NAS, 1980). Shittimwood is outstandingly drought hardy (Ecocrop, 2011).

For optimal growth, shittimwood requires hot temperatures with an average annual temperature ranging from 18.7°C to 27.8°C, and annual rainfall above 350 mm (but it tolerates 87 up to 2300 mm rainfall). It prefers clayey soils but can be found on stony ground or heavy clays with a pH ranging from 5 to 8. It is a salt tolerant species and it can withstand periodic flooding as well as waterlogging (Ecocrop, 2011; Orwa et al., 2009). Shittimwood is tolerant of forest and grass fires (Ecocrop, 2011). Shittimwood seedlings are not sensitive to browsing by mammals or rabbits but its growth may be seriously hampered by insects and soil fauna (Rahman et al., 1977).

Environmental impact 

Shittimwood is probably a N-fixing tree (Ecocrop, 2011). It also provides shade to livestock during dry periods (Orwa et al., 2009).

Nutritional aspects
Potential constraints 

This species has been reported to contain 18-20% tannin in bark and pods (Orwa et al., 2009; Duke, 1983). This may limit the nutritive potential of Acacia seyal (Osuga et al., 2007), although no toxic effects were observed in sheep and goats when more than 30% Acacia seyal was included in the diet (Ebong, 1995).

Ruminants 

The pods and leaves of Acacia seyal are nutritious and palatable to livestock (Orwa et al., 2009). Leaves contain about 16% protein (11-20% DM, though higher values have been reported), 20-35% NDF and 12-25% ADF. Pods are richer in protein, with 15-24% in the DM (Feedipedia, 2011).

The smooth greenish-yellow bark, thick and soft when fresh, is extensively used for feeding livestock during the dry season, usually by cutting the tree to a height of about 1.5-2.5 m or by trimming off the thick branches so that the animals can browse the bark on the ground. Up to 5-6 kg/day is claimed to be sufficient for maintenance and even some milk production (Göhl, 1982). Bark contains less than 10% protein (Feedipedia, 2011).

Palatability

The pods, leaves and flowers of Acacia seyal are palatable to livestock (Göhl, 1982). The level of astringent tannins should make it less palatable than other legume browse species such as Acacia nilotica and Sesbania sesban but the reverse was found, which was attributed to tannin loss during drying (Ebong, 1995).

Several studies have compared the preference of cattle, sheep and goats for Acacia seyal and other browse species in Sub-Saharan Africa. In the Sahelian zone of Burkina Faso, farmers considered shittimwood to be a major browse species for sheep and goats. However, tracking studies showed that sheep and goats browsed shittimwood much less than other species (notably Guiera senegalensis for sheep and Acacia senegal for goats) and that it was mostly browsed during the rainy and post-rainy seasons. Cattle browsed it less than sheep and goats (Sanon et al., 2007). A previous survey in Sahelian Burkina Faso showed than fodder trees, including Acacia seyal, represented a very small part of livestock diets (and particularly of cattle diets), even when there is little grass available during the dry season (Piot et al., 1980).

In Sahelian Cameroon, Acacia seyal leaves were one of the preferred feeds browsed by sheep and goats, and the preferred one during the rainy season (other preferred species were Acacia senegal, Pterocarpus lucens and Ziziphus mauritiana, which was the preferred browse during the post-rainy and dry seasons) (Ngwa et al., 2000).

Digestibility and degradability

Shittimwood was found to have a moderately degradable DM (52-55%) and one of the least degradable protein (40%) when compared to other browse species from natural pastures in Senegal (Fall Touré, 1991). Apparent N digestibility was 16.0-22.8% lower for teff (Eragrostis tef) straw-based diets supplemented with Acacia seyal than for diets supplemented with Acacia nilotica or Sesbania sesban. Rumen ammonia and N retention were also lower (Ebong, 1995). This lower N degradability or digestibility has been attributed to the high lignin and N-ADF (11% of total N) contents found in this species (Fall Touré, 1991), and to differences in types and levels of tannin and related polyphenols (Ebong, 1995).

Sheep and goats

In Uganda, supplementation of sheep and goat diets based on teff straw with Acacia seyal, Acacia nilotica and Sesbania sesban browse resulted in similar straw intakes for all supplements. Acacia seyal represented 37% of total DMI. Sheep consumed more Acacia seyal (+ 9%) than goats, and DM, OM and NDF digestibilities were lower in sheep, due to differences in retention times (Ebong, 1995).

In Ethiopia, supplementation of sheep diets based on teff straw with Acacia seyal leaves (40% of the diet) resulted in a growth of 10 g/d, comparable to that obtained with Sesbania sesban supplementation. Neutral detergent-soluble N in the faeces was highest for sheep fed Acacia seyal, indicating higher excretion of microbial and endogenous N in the faeces. Intake of Acacia seyal increased over time (Reed et al., 1990).

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 93.7 1.4 92.9 95.3 3
Crude protein % DM 18.2 2.3 14.7 20.9 6
Crude fibre % DM 26.5 3.8 20.2 30.6 6
NDF % DM 40.9 38.8 43.0 2
ADF % DM 30.7 2.9 27.7 33.4 3
Lignin % DM 8.5 7.6 9.4 2
Ether extract % DM 2.8 0.7 1.9 3.5 4
Ash % DM 6.6 1.4 5.5 9.3 6
Gross energy MJ/kg DM 18.9 *
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 11.1 2.7 7.6 13.3 4
Phosphorus g/kg DM 2.8 0.7 2.0 3.7 4
Potassium g/kg DM 12.5 11.7 13.4 2
Magnesium g/kg DM 2.6 2.6 2.6 2
Manganese mg/kg DM 20 1
Zinc mg/kg DM 23 1
Copper mg/kg DM 8 1
 
Secondary metabolites Unit Avg SD Min Max Nb
Tannins (eq. tannic acid) g/kg DM 33.5 31.6 35.4 2
 
Ruminant nutritive values Unit Avg SD Min Max Nb
OM digestibility, Ruminant % 85.6 *
Energy digestibility, ruminants % 83.3 *
DE ruminants MJ/kg DM 15.7 *
ME ruminants MJ/kg DM 12.5 *
 
Pig nutritive values Unit Avg SD Min Max Nb
Energy digestibility, growing pig % 48.5 *
DE growing pig MJ/kg DM 9.1 *

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

References

CIRAD, 1991; FUSAGx/CRAW, 2009; Russell, 1947

Last updated on 24/10/2012 00:45:03

Main analysis Unit Avg SD Min Max Nb
Dry matter % as fed 30.0 5.3 23.0 35.7 4
Crude protein % DM 19.9 2.8 17.1 23.8 5
Crude fibre % DM 21.7 2.1 18.6 24.1 5
NDF % DM 37.5 1
ADF % DM 25.7 1
Lignin % DM 6.7 1
Ether extract % DM 1.5 0.5 0.9 2.1 5
Ash % DM 5.9 0.8 5.1 7.0 5
Gross energy MJ/kg DM 18.6 *
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 9.0 1.3 7.3 10.4 5
Phosphorus g/kg DM 3.5 0.6 2.8 4.3 5
Potassium g/kg DM 59.0 78.9 12.9 150.1 3
Magnesium g/kg DM 12.9 17.4 2.8 33.0 3
Manganese mg/kg DM 56 55 56 2
Zinc mg/kg DM 43 29 57 2
Copper mg/kg DM 7 7 7 2
 
Ruminant nutritive values Unit Avg SD Min Max Nb
OM digestibility, Ruminant % 87.2 *
Energy digestibility, ruminants % 83.3 *
DE ruminants MJ/kg DM 15.5 *
ME ruminants MJ/kg DM 12.4 *
 
Pig nutritive values Unit Avg SD Min Max Nb
Energy digestibility, growing pig % 56.0 *
DE growing pig MJ/kg DM 10.4 *

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

References

CIRAD, 1991; Russell, 1947

Last updated on 24/10/2012 00:45:03

Main analysis Unit Avg SD Min Max Nb
Dry matter % as fed 44.9 4.7 38.9 52.6 6
Crude protein % DM 15.6 2.5 10.7 21.4 32
Crude fibre % DM 15.2 6.6 8.4 28.5 14
NDF % DM 26.7 6.2 20.2 42.4 16
ADF % DM 17.3 5.2 12.5 31.3 18
Lignin % DM 5.8 3.5 1.8 16.7 17
Ether extract % DM 4.2 1.7 1.7 7.6 14
Ash % DM 8.3 1.6 6.1 12.6 31
Gross energy MJ/kg DM 18.2 *
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 22.6 12.4 6.4 49.0 15
Phosphorus g/kg DM 1.6 0.5 0.4 2.4 15
Potassium g/kg DM 10.4 3.7 4.1 18.2 13
Sodium g/kg DM 0.5 0.4 0.0 0.8 5
Magnesium g/kg DM 2.6 0.8 1.3 4.0 14
Manganese mg/kg DM 64 36 32 113 6
Zinc mg/kg DM 27 8 17 39 6
Copper mg/kg DM 14 19 6 54 6
Iron mg/kg DM 418 1
 
Secondary metabolites Unit Avg SD Min Max Nb
Tannins (eq. tannic acid) g/kg DM 114.3 164.4 0.0 480.0 7
Tannins, condensed (eq. catechin) g/kg DM 22.3 9.3 12.0 30.0 3
 
Ruminant nutritive values Unit Avg SD Min Max Nb
OM digestibility, Ruminant % 80.2 *
OM digestibility, ruminants (gas production) % 54 52 56 2
Energy digestibility, ruminants % 76.6 *
DE ruminants MJ/kg DM 14.0 *
ME ruminants MJ/kg DM 11.4 *
ME ruminants (gas production) MJ/kg DM 7.6 7.2 8.0 2
a (N) % 26.0 1
b (N) % 46.0 1
c (N) h-1 0.024 1
Nitrogen degradability (effective, k=4%) % 43 *
Nitrogen degradability (effective, k=6%) % 39 *

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

References

Abdulrazak et al., 2000; CIRAD, 1991; Ebong, 1995; Fadel Elseed et al., 2002; Fall Touré, 1991; Russell, 1947

Last updated on 24/10/2012 00:45:03

Main analysis Unit Avg SD Min Max Nb
Dry matter % as fed 93.1 92.5 93.7 2
Crude protein % DM 6.4 3.0 4.3 10.6 4
Crude fibre % DM 23.5 2.8 20.7 27.1 4
Ether extract % DM 0.9 0.2 0.7 1.1 4
Ash % DM 10.0 2.9 6.6 13.3 4
Gross energy MJ/kg DM 17.0 *
 
Minerals Unit Avg SD Min Max Nb
Calcium g/kg DM 37.5 8.4 25.0 42.8 4
Phosphorus g/kg DM 0.4 0.2 0.2 0.7 4
Potassium g/kg DM 7.3 5.1 9.6 2
Sodium g/kg DM 0.1 1
Magnesium g/kg DM 1.2 1.1 1.4 2

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

References

CIRAD, 1991; Dougall et al., 1958

Last updated on 24/10/2012 00:45:03

References
References 
Datasheet citation 

Heuzé V., Tran G., Boval M., 2015. Shittimwood (Acacia seyal). Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. http://www.feedipedia.org/node/341 Last updated on October 6, 2015, 16:40

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