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Red bush willow (Combretum apiculatum)

Datasheet

Description
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Common names 

Red bush willow, sabi willow, bush willow [English], rooiblaar, rooiboswilg [Afrikaner]; umbhondo [Ndebele]; mohwelere [Sepedi]; bonda, chikukute, mudziyaishe, mugodo, mugoro, ndhuva, tsingidzi [Shona]; imbondvo [Swazi]; muvuvha [Tshivenda]; mohwidiri [Tswana]; umbondwe [Zulu]

Description 

Red bush willow (Combretum apiculatum Sond.) is a deciduous, small to medium-sized tree reaching 10 m in height that is found in many savannah areas of tropical eastern Africa and of southern Africa. It is widely browsed by wild and domestic ruminants.

Morphology

Combretum apiculatum is a deciduous, small to medium-sized tree growing to a height of 10 m. It is not a climbing species, unlike other Combretum species. It has a deep root and is a single or multi-stemmed species with a short, often curved trunk and a scanty, irregular crown. The slender branches are dropping and provide the tree a willow-like habit. The bark of the trunk is initially smooth but becomes fissured and scaly with age, grey to dark grey or brownish grey in colour. The leaves are thin, shiny, yellow green in colour in summer and brownish red or yellow in winter. They are opposite or borne in whorls of 3 at the nodes. The leaf blade is 3-14 cm long x 1.5-7.5 cm wide and may have sharp twisted tips, hence the epithet apiculatum. The flowers are fragrant, yellow to creamy green in colour. They are borne in groups of 3-4 on axillary, shortly petiolated spikes of new shoots. Flowering occurs during spring and summer. The fruits are nearly spherical, 4-winged, one-seeded, 3 cm long x 2.5 cm broad. They are sticky and green when young and they become glossy yellowish-green to reddish brown at maturity. The fruits remain on the tree up to the next flowering season (Hyde et al., 2019; Becking, 2018; Masupa et al., 2011). 

Uses

Combretum apiculatum can be used as fodder for livestock and wildlife provided they do not eat the seeds, which are poisonous and eaten only by the brown-headed parrot (Poicephalus cryptoxanthus) (Masupa et al., 2011). The scented flowers are attractive to bees and ants. The wood, which is hard and resistant to termites, is used to make fence posts, wheel spokes and small furniture. Red bush willow is used as an ornamental with nice autumn colours and makes a nice shade tree (Masupa et al., 2011). Extracts have been reported to have several biological activities like anthelminthic effect, antischistosomal activity and antibacterial effect (Lima et al., 2012).

Distribution 

Combretum apiculatum is widespread in many countries of tropical eastern and southern Africa: Kenya, Tanzania, Angola, Botswana, Malawi, Mozambique, Namibia, Zambia, Zimbabwe and South Africa. It is found in dry open woodland and savannah, and is considered an indicator of mixed veld in South Africa. It is naturally occuring from sea level up to 1400-1500 m altitude where rainfall is average or in semi-arid areas. Red bush willow can grow on sandy, granitic or rhyolitic soils as well as in rocky places on basalt plains. Once established, the tree is frost and drought resistant (Hyde et al., 2019; Becking, 2018; Masupa et al., 2011).

Forage management 

A simulation of goat browsing indicated that browsing by mammals enhanced shoot growth and leaf production of Combretum apiculatum (Rooke, 2003). It was reported to withstand severe defoliation (100%) without compromising growth of the tree in the short term, though this could have a detrimental effect on the future growth seasons (Rooke et al., 2006).

Environmental impact 

Quality pasture indicator

In South Africa, Combretum apiculatum was reported to be an indicator of mixed veld, an intermediary form of natural rangeland between sweetveld, which is palatable year-round, and sourveld, which is poorly palatable during winter (Macaskill, 2016).

Nutritional aspects
Nutritional attributes 

Based on the few data available, Combretum apiculatum has a low nutritive value, with a low protein content (< 11% DM) that does not change during the year (Lukhele et al., 2003). The fibre content seems also moderate (ADF 25% DM).

Potential constraints 

Foliage

Combretum apiculatum foliage may contain high amounts of condensed tannins, though a proper quantification is needed (Lukhele et al., 2013).

Seeds

Combretum apiculatum seeds have been reported to be poisonous (Masupa et al., 2011).

Ruminants 

Fresh Combretum apiculatum foliage collected on the trees was assessed as a protein supplement to grasses or crop residues for livestock feeding. The composition and digestion parameters were studied. The medium-low protein content of the foliage was found to be insufficient for livestock grazing on poor quality grass and protein availability was thought to be reduced by its high tannin content. It could however be recommended in periods of grass scarcity (Lukhele et al., 2003).

Palatability

Combretum apiculatum is known to be browsed by wild ruminants. In the Mopani woodland of South Africa, during the wet season the greater kudu (Tragelaphus strepciseros) relishes on red bush willow which represents the largest portion of the female diet (44%) and of the male diet (34%) (Makhado et al., 2016a). During the dry season the red bush willow foliage intake dropped to 5% only (Makhado et al., 2016b). In natural reserves, Combretum apiculatum was reported to be an important source of fodder for giraffes almost all year at the exception of the few weeks whent the tree sheds its leaves. The red bush willow foliage intake of giraffes was positively correlated with protein and moisture content (Sauer et al., 1982).

Digestibility and degradability

In vitro OM digestibility and in situ DM degradability were both reported to be about 60% (Lukhele et al., 2013).

Goats

In Botswana, Combretum apiculatum foliage was used to replace alfafa in the diet of Tswana goats fed on a basal diet of Cenchrus ciliaris. There were no difference in feed intake, in water intake, and in growth performance between animals fed on alfalfa and those fed on Combretum apiculatum. It was concluded that goats could be supplemented with red bush willow foliage (Aganga et al., 1999).

Rabbits 

No information seems available in the international literature on the use of Combretum apiculatum leaves in rabbit feeding (August 2019). However, since some positive results were obtained with ruminants such as goats for example (see Ruminants section above) some experiments with rabbits would be welcome. However, as long as results of such experiments are not available, use of this low fibre and low protein forage may not be recommended in rabbit feeding. As for other herbivorous animals, seeds of Combretum apiculatum must be considered as toxic for rabbits.

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

Main analysis Unit Avg SD Min Max Nb  
Dry matter % as fed 47.5       1  
Crude protein % DM 11.7 0.6 10.7 12.4 7  
Crude fibre % DM 19.3   17 21.6 2  
Neutral detergent fibre % DM 31.9 1.9 27.8 33.4 7  
Acid detergent fibre % DM 23 2.7 18.6 26.1 7  
Lignin % DM 4.7 1.8 2.6 8 7  
Ether extract % DM 4.2 0.7 3.6 5.4 6  
Ash % DM 6.3 1.9 5.1 10 6  
Gross energy MJ/kg DM 18.7         *
               
Minerals Unit Avg SD Min Max Nb  
Calcium g/kg DM 13.3 7.5 8.9 28.4 6  
Phosphorus g/kg DM 1.3 0.4 0.9 1.9 6  
Potassium g/kg DM 7.6 3.2 5.7 13.3 5  
Sodium g/kg DM 0.09 0.12 0.04 0.3 5  
Magnesium g/kg DM 3.2 0.4 2.8 3.8 5  
Manganese mg/kg DM 132 118 29 320 5  
Zinc mg/kg DM 21 7 13 31 5  
Copper mg/kg DM 30 23 8 66 5  
Iron mg/kg DM 347 95 178 399 5  
               
In vitro digestibility and solubility Unit Avg SD Min Max Nb  
In vitro DM digestibility (pepsin) % 52       1  
In vitro OM digestibility (pepsin) % 59 5 51 64 5  
               
Ruminants nutritive values Unit Avg SD Min Max Nb  
OM digestibility, ruminants % 60          
Energy digestibility, ruminants % 57.4         *
DE ruminants MJ/kg DM 10.7         *
ME ruminants MJ/kg DM 8.8         *
Nitrogen degradability (effective, k=6%) % 28       1 *
Nitrogen degradability (effective, k=4%) % 32       1 *
a (N) % 4       1  
b (N) % 44       1  
c (N) h-1 0.072       1  
Dry matter degradability (effective, k=6%) % 60       1 *
Dry matter degradability (effective, k=4%) % 66       1 *
a (DM) % 35       1  
b (DM) % 59       1  
c (DM) h-1 0.045       1  

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

References

Aganga et al., 1999; Balogun et al., 1998; Groenewald et al., 1967; Lukhele et al., 2003

Last updated on 06/11/2019 14:15:38

References
References 
Datasheet citation 

Heuzé V., Tran G., Lebas F., 2019. Red bush willow (Combretum apiculatum). Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. https://www.feedipedia.org/node/164 Last updated on November 6, 2019, 15:35

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