The Potential of Tapping Palm Trees for Animal Production (PART 1)


Christophe DALIBARD
Animal Production Officer
Feed Resources Group


Palm trees have proved to be efficient converters of solar energy into biomass in most agro-ecological zones of the tropical world. Most tapped palm trees gives a sap very rich in sugar (10 to 20%). For several millennia, many species of palm trees (including coconut) have been used for sugar production. Highly sophisticated techniques of tapping were developed through the centuries in Asia, Africa and America. High yields of sugar were obtained from palms that could continue for up to a hundred years of production. One of the main constraints on production in recent times has been the increasing lack of fuel needed for processing palm sap into sugar and the price thereof. Nevertheless, since trials of feeding pigs with fresh sugar palm sap were successfully initiated in an FAO project in Cambodia, there has been renewed interest in tapping palm trees for sap to be used as feed. A thorough review of the literature has shown that intensive pig rearing based on palm sap has already been practised by the Indonesians for centuries and was found to be a very efficient system for intensifying agriculture in some highly populated islands. In today's economy, developing animal production using palm sap as the main source of energy in the diet looks very promising: the land could sustain higher population densities through the intensification of crop and animal production within sustainable integrated systems for small farmers.


For centuries, many palm species have been tapped throughout the tropical world in order to produce fresh juice (sweet toddy), fermented drinks (toddy, wine, arak), syrup ("honey"), brown sugar (jaggery) or refined sugar. Most tapped palm trees do not only produce sap but are multipurpose (edible fruits, building materials, fibres, wax, etc.) and their socio-economic importance can be critical for the rural poor. Palm trees are also often associated with crops and pastures.


Theoretically, the advantages of taking the sugars from the sap before it goes to the fruits are obvious. These sugars are intercepted before being used in the production of the non-edible parts such as husk in coconut, which represents 35% of the fruit (Rangaswami, 1977), and in the production of edible material through chemical reactions which imply a loss, mainly a conversion of sugar into oil as for coconut and oil palm. It is therefore more profitable from the point of view of edible energy production to tap a palm for the sap rather than allowing the palm to produce fruits. Similarly, it was demonstrated that, in the context of harvestable energy from the coconut palm, the amount of energy harvested in the sap (through production of ethanol) could be 5 to 7 times higher than from the oil of the nuts (Banzon, 1984).


It is possible to obtain a sugary solution by the excision of the meristem in nearly all palms (Tuley, 1965). Basically, starch reserves from the trunk are converted to sugar and are transported upwards to the stem apex (Fox, 1977). Although this is true in the case of Corypha, other explanations are needed for palms such as coconut which does not accumulate starch in its trunk (Reijne, 1948, cited by Van Die, 1974). Pethiyagoda (1978) describes the upward stream as a watery liquid containing dissolved salts absorbed from the soil, and the downward stream as a comparatively rich mixture of food (principally sugars) manufactured in the leaves. The sap flow is intercepted by injuring fibro-vascular tissues of the apex or of the inflorescence. Nevertheless, this author recognizes that the large volume of exudate produced during tapping and the high sugar concentration clearly indicate that the material is drawn from stored resources and is in excess of currently synthesised sugars. The origin of the large flow of sap that occurs in a tapped tree is not yet clearly demonstrated. This is also the case for Borassus flabellifer where water from root absorption appears quite insufficient (Kovoor, 1983). Pethiyagoda (1978) suggests that there is a steep rise in respiration which occurs whenever there is a rapid solubilisation and movement of materials from sites of storage to the points at which they are needed such as during seed germination, flower opening and fruit ripening. This phenomenon can be fostered, heightened and sustained by manipulative processes, the use of generally young growing sites (merismatic tissues) and the act of freshening the wound. Preliminary studies (not published) cited by Pethiyagoda (1978) show a considerably increased respiration by fragments of coconut inflorescence drawn from stimulated spadices.


Table 1 lists nearly 30 different palm species that are traditionally tapped in parts of the tropical world. The major part of the information was found on palms that are tapped in the Old World, with more or less as many different tapped species in Asia and in Africa. It has been possible to identify only three tapped palm species in the New World (Carnauba cerifera, Jubaea spectabilis and Mauritia flexuosa) and very little literature seems to be available on tapping these trees. In America and Africa, it seems that tapping palms has been practised exclusively or mainly for wine production, whereas in Asia the sap is used either as fresh juice or processed into a large array of products (wine, arak, sugar, vinegar, etc.). Table 1 also shows that there are tapped palm species adapted to almost all agro-ecological zones of the tropical world from tidal areas and swamps to deserts and mountains.

Table 1: Location and management of tapped palm species

Latin name               Regions and management
Areca catechu            Tropical rain forest S & SE Asia;
                         Improved cultivated palm [1]

Arenga pinnata           Tropical rain forest into dry forest
or saccharifera          SE Asia; Unimproved cultivated or
Arenga undulatifolia     managed palm [1]

Beccariophoenix          Central Madagascar (1,000m)

Borassus aethiopium      Tropical savanna Africa; Semi-wild
                         or wild palms [1]

Borassus flabellifer     Tropical forest into savanna Asia;
Borassus sundaicus       unimproved cultivated or managed
                         palm [1]

Borassus                 Along rivers Madagascar [2]

Carnauba cerifera        Brazil

Caryota urens            Tropical rain forest Asia & S
                         Pacific; Unimproved cultivated or
                         managed palm [1]

Cocos nucifera           Coastal tropical rain forest
                         E Africa, Asia & Pacific; Improved
                         cultivated palm [1]

Corypha elata            SE Asia

Corypha umbraculifera    Tropical rain forest S & SE Asia;
                         Unimproved cultivated or managed
                         palm [1]

Elaeis guineensis        W Africa, Madagascar [2], Indonesia
                         [4]; Improved cultivated palm [1]

Hyphaene coriacea        SE Africa

Hyphaene thebaica        Semi-deserts & deserts of E Africa;
                         Unimproved cultivated or managed
                         palm [1]

Hyphaene shatan          Madagascar

Jubaea spectabilis       Chile

Mauritia flexuosa        Tropical rain forest Peru; Semi-wild
                         or wild palms [1]

Nypa fruticans           Tidal areas Asia; Unimproved
                         cultivated or managed palm [1]

Phloga polystachya       Madagascar [2]

Phoenix dactylifera      Semi-desert N. Africa; Improved
                         cultivated palm [1]

Phoenix reclinata        Coast W & SE Africa [5][3][4][6]

Phoenix sylvestris       Trop. rain forest to 1,500m [1];
                         India, Bangladesh, Ivory Coast;
                         Unimproved cultivated or managed
                         palm [1]; Bangladesh: plantations [7]

Raphia hookeri,          Tropical rain forest W Africa,
R. vinifera,             Madagascar [2]; Semi-wild or wild
R. sudanica,             palms [1]
R. ruffia

References: [1] Johnson, 1987; [2] Decary, 1964; [3] Giffard, 1967; [4] Blanc-Pamard, 1980; [5]Cunningham, 1990; [6] Adand:S, 1954; [7] Annett, 1913.


The techniques for tapping palms are numerous and can vary drastically from one continent to another, as demonstrated by the case of Borassus aethiopium in Africa and Borassus flabellifer in Asia. Refined techniques of tapping the inflorescence of the latter are compatible with production in the long term. Destructive techniques are usually practised on the terminal bud of B. aethiopium and are often responsible for the death of the tree within a few months. The African oil palm is used in Africa for producing wine mainly through two different techniques: one is destructive (incision of stem apex of felled palm) and is preferred in Ghana; the other is not destructive (excision of male inflorescence) and has been developed where economic considerations have forced the people to preserve their palms, e.g. in eastern Nigeria (Hartley, 1977). The excision of the terminal bud of standing trees is quite harmful since tapped palms never resume vigorous growth. If the terminal bud is only perforated, then the trees will show malformation in subsequent leaves, flowers and trunk growth (Kovoor, 1983). Nevertheless, it has been observed that multi-stemmed trees such as Hyphaene coriacea and Phoenix reclinata in south-eastern Africa generally recoppice after tapping, although tapped stems die unless tapping is stopped before the apical meristem is totally destroyed (Cunningham, 1990). The very low yields of sap from these trees are interpreted as a result of over exploitation. Cunningham (1990) suggests that if palm size classes shifted to the extent that there was again a high proportion of mature fruit-bearing palms in the population, then inflorescence tapping could be practised.

The most advanced method of tapping is that applied to the inflorescence spadix which guarantees a high yield for long periods without affecting the well-being of the tree. It only entails a sacrifice of a bunch of fruit in the case of tapping female inflorescences. Tapping the inflorescence is practised throughout S.E. Asia on all species of tapped palm trees (Kovoor, 1983). Two features are common in tapping: manipulative treatment or preparation (application of chemicals and substances of plant origin, twisting, distortion, kneading, pounding, bruising, beating or tapping) necessary as a prelude to copious and sustained sap flow, and renewing the exuding wound by shaving off a thin slice of tissue once or twice a day (Pethiyagoda, 1978). Tapping is an art: sap yields depend on the skills of the tapper (Khieu, 1996; Coconut Research Institute, 1967).

Except for Nypa fruticans, which is trunkless and develops its inflorescence at a height of about 1m (Hamilton and Murphy, 1988), other palm trees have to be climbed for tapping as their inflorescences are located at the summit of their trunk which is often over 10m high. Various methods are used to climb the tree (six recorded by Kovoor, 1983), using ankle-loops, aerial ropeways between trees, hoop-belt, rivetted bamboo, mobile 4-9m long ladders and fixed ones on the upper part of the trunks, notches in the trunk, etc.


The management of palm trees for sap production varies very much according to species. Nypa fruticans, Phoenix sylvestris, Elaeis guineensis, Raphia hookeri and Cocos nucifera can be tapped at a rather early age, respectively when the trees are 4, 5, 6, 7 and 7 years old (Crevost and Lemari:S, 1913; Abedin et al., 1987; Essiamah, 1992; Profizi, 1988; Levang, 1988). On the other hand, many years are needed before tapping Caryota urens (10 to 15), Borassus flabellifer (15 to 30) or Corypha elata (20 to 100) (Redhead, 1989, Fox, 1977).

The number of years a palm tree can be tapped is also very different depending on the species. Corypha elata and Raphia hookeri flower just once. They will produce sap only for a few months before dying (Fox, 1977; Profizi, 1988). Arenga pinnata and Caryota urens will produce sap for several years, with large interruptions in the case of Caryota urens as it flowers only every two or three years (Redhead, 1989; Dissanayake, 1977). Other palm trees will produce sap for much longer periods: 10 to 15 years for Elaeis guineensis, more than 20 years for Cocos nucifera, 50 years for Nypa fruticans and Phoenix sylvestris and 30 to 100 years for Borassus flabellifer (Adand:S, 1954; Levang, 1988; Magalon, 1930; Abedin et al., 1987; Lubeigt, 1977).

Some species are able to produce sap all year round: Arenga pinnata, Cocos nucifera, Elaeis guineensis and Nypa fruticans (Mogea et al., 1991; Rangaswami, 1977; Tuley, 1965; Kiew, 1989). Borassus flabellifer and Phoenix sylvestris produce only seasonally (Crevost and Lemari:S, 1913; Annett, 1913).


Most tapped palm trees gives a sap very rich in sugar (10 to 20% according to species and individual variation). The yields are highly variable according to the species and their management. Under proper management, the main tapped palm species (Arenga pinnata, Borassus flabellifer, Cocos nucifera and Nypa fruticans)can reach yields of about 20 tonnes of sugar per hectare (Van Die, 1974; Watson cited by Kiew, 1989). Compared to sugarcane production (5-15 tonnes of sugar/ha/year), the Borassus flabellifer tree can reach 18 tons/ha/year under rain-fed conditions (Khieu, 1996) and the coconut tree 19 tons/ha/year (Jeganathan, 1974). According to estimates, Elaeis guineensis produces much less sugar (1.2 tonne per hectare, Udom, 1987) but, as it has never been exploited for sugar production but only for wine production, there are good prospects for obtaining much higher yields in a production system oriented towards sugar production.


Most palm trees have multipurpose uses. Nevertheless, they are not always compatible. Sap production is at its maximum just before or during fruit formation. Tapping the tree competes with the production of the ripening fruit (Redhead, 1989). Tapping can also stimulate fruit production: a young coconut palm tapped during 6-12 months for sugar production will then produce more nuts (Magalon, 1930; M.F., 1925). A technique called sequential coconut toddy and nut production has been developed in the Philippines at the Davao Research Centre. The first half of the spathe is tapped and the second half is left for fruit production as female flowers that develop to mature nuts are situated in this lower portion. Nut and copra yields are about 50% lower than non-tapped palms; however, this technique has been demonstrated to be very feasible and highly profitable for small producers (Maravilla and Magat, 1993). Arenga pinnata can be tapped when they are between 12-15 and more than 30 years old; then they can be cut for sago production (Sumadi, 1988). Nevertheless, in West Java, where sago is obtained from trees 10-12 years old, no tapping will be done previously, farmers arguing that it would reduce the quantity of starch in the trunk (Mogea et al., 1991). In Eastern Nigeria, oil palms that have been abandoned as uneconomic bunch producers usually give good economic returns for wine production before old plantings are cleared and replanted (Tuley, 1965).

There are various types of palm-crop associations in Bangladesh. Phoenix sylvestris and Borassus flabellifer can both be associated with several of the following crops: rice, wheat, chickpea, mustard, jute, lentil, potato, linseed, winter vegetables and sugarcane (Abedin et al., 1987).

Palm trees often have advantages compared with other crops as far as sustainability is concerned: in parts of west Java where Arenga pinnata is still tended in groves, soils appear much more stable and productive of other crops than where cassava is cultivated (Dransfield, 1977). Furthermore the advantages of this tree are its great ecological tolerance, its ability to grow and stabilize unproductive erosion-prone sites such as steep dryland slopes (e.g., coffee orchards in North Sulawesi, Mogea et al., 1991), its potential to grow on almost any type of soil, to increase soil fertility and water conservation, its great tolerance of accidental burning (the only surviving tree in the Minahassa, Sulawesi after volcanic activity), the relatively fast growth rate, the fact that it needs almost no maintenance and usually does not suffer from any serious pests or disease, and the wide range of secondary or alternate products obtainable (Mogea et al., 1991).

Borassus flabellifer is often planted on paddy fields boundaries in Cambodia and India. The effect of shading on understorey crops are likely to be negligible due to the small-sized crowns and to the large space (10-15m) between trees (Jambulingam and Fernandes, 1986). Like Arenga pinnata, this tree thrives in reputedly the poorest, infertile and arid regions. It also suffers remarkably little from prolonged flooding. It is extraordinarily pest and disease-resistant, requiring limited means of cultivation if any. As it grows in sandy plains, it is used for blocking erosion and fixing dunes, thanks to its deep root system (Kovoor, 1983). It is also, like Corypha elata, a fire resistant palm that is a pioneer species on regularly burnt land such as those exploited by the slash-and-burn technique (Ormeling (1956), cited by Fox, 1977). It is used in Burma as a wind-break in areas cropped with groundnut (Lubeigt, 1977). It plays a major role in Savu and Roti islands (Indonesia) where the soil fertility is a crucial constraint. Traditional slash-and-burn system which is currently practised in neighbouring islands (Timor and Sumba for example) has been replaced by semi-permanent gardening through the use of large amounts of old Borassus leaves that are burnt in the fields. This permits fertile gardens to be kept in the vicinity of the houses (Fox, 1977). Borassus forests possess a potentially unique pattern of nutrient cycling, which enables them to support relatively productive and stable forms of agriculture as well as to contribute to recovery of disturbed sites (Anderson, 1987).

In the Peruvian Amazonia, Mauritia flexuosa constitutes dense populations in seasonal swamp forests on waterlogged or sandy soils, which are generally considered as unfit for agriculture (Kahn, 1988). Unlike sugarcane, Nypa fruticans does not compete with other crops for agricultural land except where total reclamation is undertaken on mangrove land (Hamilton and Murphy, 1988).


One of the main reasons for the decline of sugar production from palm trees is the increasing lack of fuelwood and its increasing price. In the case of wine-producing palm trees, the decline often occurred under religious or colonial pressure. In Africa, some destructive techniques of tapping were responsible for the disappearance of the trees in entire areas. The important moves of population in the fifties (settlers setting up coffee, cocoa, rubber trees and oil palm plantations) were also responsible for loss of traditional codes of managing the trees and less long term concerns. Thus the traditional technique of tapping only male trees and keeping females for regeneration was abandoned (Portdlres, 1964; Blanc-Pamard, 1980). In Sri Lanka, widespread cultivation of coconut as an exported-oriented crop drastically changed the local economy and imported sugar became cheaper (Dissanayake, 1977). In Peninsular Malaysia, the swamp areas were drained for coconut plantations where Nypa fruticans was before predominant (Kiew, 1989). Fishponds developers also found great profits in various fishpond operations made possible by converting mangrove swamps, including Nypa fruticans areas, for fish production (Encendencia, 1985).

Tapping sugar palms is very labour intensive. It must be done daily otherwise the sap flow rapidly diminishes as tissue healing occurs and restarting the sap flow requires long and hard work. Whenever easier and better paid jobs were available, tapping was given up. During the colonial period in India, Borassus tappers were recruited in the British plantations abroad, particularly on the rubber and oil palm estates where their skills could be easily adapted to those required for these trees (Fox, 1977).

In many countries, in comparison to other crops or commodities, there is a general lack of interest shown by the decision makers about the socio-economic potential of tapping palms. None or little research, selection of higher yielding varieties or training and extension services are funded and the tappers are seldom exposed to technological innovations if they do not generate them by themselves.

...\... ====> PART 2




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