The author's address is: Department of Animal Production and Health,
Ministry of Agriculture, Forestry and Fisheries, PO Box 177, Phnom Penh, Cambodia (e-mail:
[email protected]).
Acknowledgements. The studies reported here were financed partially by the
FAO/TCP/CMB/2254 Project, the International Foundation for Science (B/2353-1) and SAREC
(research as partial fulfilment of the requirements for an M.Sc. in livestock-based
sustainable farming systems).
Le palmier � sucre est un �l�ment important de la vie rurale au Cambodge. Il fournit divers produits d'usage domestique. Les feuilles et le tronc servent de mat�riel de construction. Le suc, extrait des inflorescences, est traditionnellement transform� en sucre, consomm� sous forme de boissons fra�ches et ferment�es, ou encore donn� en nourriture aux cochons. Certaines parties de son fruit sont �galement consomm�es. Les �tudes mentionn�es dans l'article avaient au d�part pour but de mettre au point de nouvelles utilisations du jus de palmier � sucre en tant qu'aliment �nerg�tique pour les porcins. Pour ce faire, le rendement en jus des arbres appartenant � 12 m�nages a �t� mesur� � intervalles mensuels pendant la saison de r�colte 1995 (de janvier � mai). Dans les m�nages pauvres, les porcs ont engraiss� � un taux oscillant entre 250 et 550 g/jour lorsqu'ils �taient aliment�s avec du jus frais de palmier � sucre et des quantit�s limit�es (moins de 200 g de prot�ines/jour) de soja ou de poisson s�ch�. Le rendement en jus s'est �tabli entre 2,7 et 7,5 kg/arbre/jour, sur une p�riode de cinq mois, avec une concentration moyenne en sucre de 13 pour cent. Chaque arbre couvrant une superficie d'environ 50 m�, il a �t� estim� qu'un tel rendement �quivalait � une production de sucre de 10 � 27 tonnes par hectare et par an. Une telle productivit� en �nergie digestible est sup�rieure � celle de toutes les autres cultures, temp�r�es et tropicales, et est particuli�rement remarquable si l'on consid�re que le palmier � sucre n'est jamais fertilis�.
La palma de az�car es un elemento importante de la vida rural en Camboya. Proporciona distintos productos para uso dom�stico. Las hojas y el tronco se utilizan para la construcci�n. La savia obtenida de la inflorescencia tradicionalmente se ha transformado en az�car, que consume la poblaci�n en forma de bebidas frescas y fermentadas, o bien se administra a los cerdos. Tambi�n se comen algunas partes del fruto. Los estudios descritos en el presente art�culo se orientaron inicialmente a la b�squeda de aplicaciones alternativas del jugo de la palma de az�car como pienso energ�tico para los cerdos. En el curso del trabajo se midi� a intervalos mensuales el rendimiento de jugo en �rboles pertenecientes a 12 familias durante la temporada agr�cola de 1995 (enero-mayo). Los cerdos de los hogares agr�colas pobres crec�an a un ritmo comprendido entre 250 y 550 g/d�a cuando se les administraba jugo fresco de palma de az�car y cantidades limitadas (menos de 200 g de prote�nas/d�a) de habas de soja o de pescado seco. El rendimiento de jugo oscil� entre 2,7 y 7,5 kg/�rbol/d�a durante un per�odo de cinco meses, con una concentraci�n media de az�cares del 13 por ciento. Se estima que, puesto que cada �rbol ocupa una superficie aproximada de 50 m2, ese rendimiento es equivalente a 10-27 toneladas de az�cares/ha/a�o. Este nivel de productividad de carbohidratos digestibles supera el de todos los dem�s cultivos, de clima templado y tropical, y es particularmente importante considerando que la palma de az�car no se fertiliza nunca.
The challenge facing scientists, researchers, extension workers and farmers in the next millennium is to find appropriate ways of utilizing the earth's resources to feed the predicted doubling of the human population while at the same time improving the living standards of rural people.
The pressure on the food supply will not only come from the increase in
the population but from the deterioration in the natural resource base caused by factors
such as deforestation, which causes flooding or drought; burning of fossil fuels, leading
to global warming; and the pollution of soil and water by the overuse of agrochemicals
such as fertilizers and pesticides. The effects of deforestation are especially serious in
Cambodia, and in one area alone - around Tonle Sap Lake - the result has been a permanent
fall in the lake's water level which has led to a reduction in the numbers of fish, a most
important source of protein for the Cambodian population.
In order to respond to these issues it has been argued that, instead of exploiting
resources for production of specific commodities, it is more appropriate to match the
farming system with the available resources (Preston and Leng, 1987). The successful
development of this strategy entails the identification of cropping systems that optimize
the use of the basal resources of sunlight, soil and water to satisfy human needs for
food, fuel, clothing and shelter. This approach takes a holistic view of human needs to
include sociocultural, economic and environmental aspects, instead of individual crop or
animal productivity as a unique paradigm.
This article illustrates the application of this approach, taking as an example the case
of the sugar palm (Borassus flabellifer), the use of which has been a traditional
feature of rural life in Cambodia. The sugar palm is one of the 200 genera and 1 500
species of palms that occur naturally in the tropics and subtropics. It attracted the
attention of development scientists in the early part of this century but has since been
largely ignored, presumably because its cultivation and utilization were not amenable to
industrial-scale management and processing.
There is now renewed interest in the sugar palm as a result of two recent developments.
One has been the declining availability and increasing cost of the fuelwood needed for
evaporating the juice to make sugar; the second has been the demonstration (Khieu Borin
and Preston, 1995) that the fresh juice could replace cereal grains in pig feeding.
The leaves of the sugar palm are commonly used as materials for construction and domestic goods. Twenty-five to 36 leaves are harvested twice a year from the palms that are not used for tapping. Farmers believe that pruning negatively affects juice production. Almost all households in rural areas use palm leaves not only for thatching but also for the walls. The top young leaves are made into hats, boxes to store rice, baskets, fans, etc. In the past they were used as writing materials, especially by the monks.
Each palm may bear eight to fifteen bunches of fruit with a total of about 80 pieces of fruit per year. The fruit generally contains two to three kernels which are eaten fresh or prepared as a sweet with sticky rice. The top part of immature fruit is also cooked as a vegetable. The fresh pulp around the kernels is reported to be rich in vitamins A and C (Morton, 1988). The mature fruit is soaked in water after which the wiry fibres are extracted. The yellow pulp is mixed with rice starch, folded inside a banana leaf and later steam-cooked.
The less-productive palm trees are cut for timber when they are move than 10 m high and about 70 to 100 years old. The whole trunk is used by removing the soft middle part, and the strong, hard outer wood is used for house construction. This outer wood is more durable than other kinds of wood when used in the shade and protected from rain. The whole trunk can also be made into a small boat capable of carrying at least three people.
Palms generally start to form inflorescences at the beginning of the dry season (November to January). The male and female inflorescences are carried on separate trees: the male tree begins to develop the inflorescence in November or December while the female tree commences one to two months later. Each palm may bear from eight to fifteen inflorescences per year. The male inflorescence lasts approximately 45 to 60 days and the female 60 to 70 days. Both male and female inflorescences are "tapped" for juice collection. Some palms, especially the female, also have inflorescences during the rainy season. Cambodian tappers have developed a technique to conserve inflorescences to be tapped after the normal harvest period.
The most important product of the sugar palm is the sap or juice, the production of which lasts for five to six months. Cambodian tappers use long bamboo poles with the stumpy remnants of leaf bases at the nodes that serve as rudimentary steps for climbing. These are rivetted permanently to the base of the trunk during the juice-collecting period. For safety reasons the tapper replaces the bamboo poles every production period (six to twelve months). When the trees are located close to each other, one or two long bamboo poles are used as an aerial "stairway" to facilitate movement between the trees, thus avoiding the need to descend and ascend each tree and permitting the tapper to use his time (there are no female tappers) more productively. Tappers are capable of tapping 20 to 30 palm trees twice a day provided an assistant is available at the base of the trunk to receive the collected juice.
Juice collection from a female palm in Takeo Province, Cambodia.
Plastic bottles used for collecting the juice are those initially used for purified
drinking-water
R�colte du suc d'un palmier � sucre potentiellement femelle dans la province de Takeo.
Les bouteilles en plastique utilis�es pour la r�colte contenaient initialement de l'eau
potable purifi�e
Recolecci�n de una posible palma hembra en la provincia de Takeo. Las botellas de
pl�stico utilizada para recoger el jugo son las usadas inicialmente para el agua potable
purificada
A palm juice tapper is slicing a female inflorescence for the
afternoon juice collection
Incision de l'inflorescence femelle d'un palmier � sucre pour la r�colte de suc de
l'apr�s-midi
Un extractor de jugo de palma est� cortando una inflorescencia femenina para la recogida
de jugo por la tarde
The inflorescences of the male and female palms are bound, beaten and
then sliced for approximately five to eight consecutive days before juice can be
collected. The tapping process is repeated every two to three days during the production
season. The inflorescences can also be preserved for later use after being processed. A
pair of rounded wooden mallets is used for the female inflorescences and flat wooden tongs
for the male inflorescences. The small fruits around the female inflorescences should not
be crushed during the preparation. The juice is channelled into a bamboo or plastic
vessel. The bamboo vessel, called an ampong, has a diameter of 10 to 15 cm, a
height of about 30 to 40 cm and can contain 2 to 4 kg of juice. For each tree an average
of four to six collection vessels are used according to the number of inflorescences being
processed at the one time. Collection is carried out twice daily (morning and afternoon)
in order to limit exposure of the juice to contamination by yeast and other fermenting
micro-organisms.
The most important technique for tapping palms is the processing of the inflorescence or
spathe. Juice production from the inflorescences is stimulated by crushing the tissues
without, however, completely destroying the cells of the crushed tissues. The time it
takes from the com-mencement of tapping to the appearance of the juice depends on the
experience of the tapper. According to the farmers in Bati district, Takeo Province, the
flowers need to be crushed and kneaded for a period of five to eight days. The juice is
then collected twice daily (early morning and late afternoon). It is usually possible to
continue tapping a single spathe until it is reduced to a stump of about 10 to 15 cm. When
the trees produce many inflorescences at the same time, the tappers are not able to
collect juice from all of them. In this case, the inflorescences are sliced and crushed
for the usual five to eight days and then preserved for juice collection some three to
five months later.
The daily production of palm juice depends mainly on the skill of each tapper. When a
tapper is replaced for a short period, the sap flow often diminishes on the day following
this replacement. Kovoor in FAO (1983) reported that the flow of juice results from the
stimulus produced by the manual operation of tapping, and thus depends on the
physiological response of the palm. There is enormous variability in daily yield per tree
and tree-to-tree juice production. Depending on the tree, weather and location, from one
to seven inflorescences may be tapped at a time. The Table demonstrates that, although the
rate of flow of the juice is reduced as the process continues, the Brix value (sugar
content) increases.
Mean juice yield and Brix value (approximate sugar content) by farm,
month, sex of trees and day of harvest
Rendement moyen en jus et valeur Brix (teneur approximative en sucre) selon
l'exploitation, le mois, le sexe de la plante et le jour de r�colte
Rendimiento medio de jugo y valor Brix (contenido aproximado de az�car) seg�n la
explotaci�n, el mes, el sexo del �rbol y el d�a en que se recoge
Juice (kg/tree/day) |
Brix value (%) |
|
Farm family |
||
Hay Yang |
4.6 |
13.4 |
Houy Kiel |
4.9 |
12.5 |
Pring Houy |
2.7 |
14.3 |
Map Chreb |
5.9 |
13.5 |
Sim Henn |
4.0 |
15.9 |
Pauv Pauv |
5.5 |
13.3 |
Tha Khorn |
5.5 |
13.5 |
Thol Onn |
6.0 |
12.2 |
Thorn Punn |
4.4 |
12.8 |
Yem Khnol |
7.5 |
11.6 |
Chhan Mak |
3.9 |
13.0 |
Thorn Chreb |
4.9 |
13.3 |
Mean |
5.0 |
13.3 |
Standard error |
�0.20 |
�0.14 |
Probability |
0.001 |
0.001 |
Month |
||
January |
4.7 |
12.6 |
February |
5.7 |
12.6 |
March |
5.2 |
13.5 |
April |
5.1 |
13.6 |
May |
4.2 |
14.1 |
Standard error |
�0.13 |
�0.09 |
Probability |
0.001 |
0.001 |
Sex of trees |
||
Female |
5.3 |
13.4 |
Male |
4.7 |
13.2 |
Standard error |
�0.09 |
�0.06 |
Probability |
0.001 |
0.005 |
Day of harvest |
||
First |
4.9 |
13.2 |
Second |
5.0 |
13.3 |
Third |
5.0 |
13.3 |
Standard error |
�0.10 |
�0.07 |
Probability |
0.665 |
0.534 |
The fresh juice starts to deteriorate naturally within a few hours after
sunrise, especially during hot weather. When the juice is collected for sugar production,
or as a drink for human consumption and for animal feeding, fermentation should be avoided
as much as possible. The normal procedure is that the collection vessels are fumigated
with the smoke of burning palm leaves or are sterilized with boiling water before being
placed under the inflorescences. However, the juice can quickly become contaminated with
wild yeasts carried by insects and airborne particles. In order to inhibit fermentation,
at least partially, a piece of bark from the white meranti tree (Shorea cochinchinensis)
is placed in the collection vessel while the juice is being collected. Another
anti-fermentation agent, lime (calcium hydroxide), is available in local markets, but
farmers do not use it, as they consider lime to have a negative effect on the quality of
sugar and the fresh juice for drinking. It has been observed that the onset of
fermentation is delayed when plastic bottles are used, presumably because they are easier
to clean and sterilize.
The naturally fermented palm juice (teck thnot chhu) is a common alcoholic beverage
in rural areas and is also used to make vinegar. Davis and Johnson (1988) reported that,
when the juice is fermented through the action of airborne micro-organisms, an alcohol
content of 5 to 6 percent may be reached. The upper alcohol limit is not necessarily set
by the quantity of sugar available in the juice, which is always in excess, but because
the natural fermenting organisms are killed at an alcohol concentration of 5 to 6 percent,
leaving a large amount of fermentable substrate.
The juice yield varies according to the sex and age of the palm, the skill of the tappers,
soil quality and the period of tapping. In a study carried out in 1995 (Khieu Borin and
Preston, 1995) in 12 farm households with an average of 20 trees each, the yield varied
from 2.7 to 7.5 kg per tree per day and the average Brix value (dissolved solids, measured
by hand refractometer) was 13.3 percent. It was found that female palms produced on
average 5.3 kg per day, compared with 4.7 kg produced by the male tree (Figure 1).
1
Sugar palm juice yield: by family, month of harvest and sex of trees
Rendement en jus des palmiers � sucre, par famille, mois de r�colte et sexe de la plante
Rendimiento de jugo de las palmas de az�car: efecto de la familia, el mes de la
recolecci�n y el sexo del �rbol
A considerable amount of energy is required to condense palm juice into syrup or sugar; about 4 kg of fuelwood is needed to produce 1 kg of palm syrup (Khieu Borin, Preston and Lindberg, 1996). Cambodian farmers continue producing palm syrup and sugar because they can still find free fuelwood and it is their main income during the dry season. However, if an opportunity cost were put on the fuelwood it would often exceed the value of the syrup produced.
Sugar palm juice is traditionally processed into three types of sugar: liquid sugar (sugar palm syrup), crystalline palm sugar and block sugar. The most common type consumed in rural areas is sugar palm syrup which is about 80 percent dry matter.
The price of cereal grains and by-products used in pig and poultry feeding is increasing rapidly. The industrial livestock sector with guaranteed market outlets for its products is still able to absorb these cost increases. But the consequences for the landless and the poorest farmers are serious as competition develops between humans and animals for the same food supply. It becomes increasingly urgent, therefore, to develop alternative feeding systems for livestock which do not use cereal grains, but which make efficient use of the products derived from the plant resources that grow most abundantly in a tropical country such as Cambodia.
The technique of feeding liquid sugar-based diets to pigs was first
developed and commercialized in Cuba using molasses derived from the processing of sugar
cane (Preston et al., 1998). Later, in Mexico, the technology was modified to use
the juice from freshly crushed sugar cane stalks (Mena, Elliot and Preston, 1981). In 1987
this system began to be applied widely in Colombia (Sarria, Solano and Preston, 1990)
stimulated by the low market prices at that time for cane sugar. Artisan crushing of sugar
cane for processing into brown sugar is a common practice in many Asian countries, and the
alternative use of the fresh juice for pig feeding was well received in remote areas of
the Philippines and Viet Nam where pig production offered a more profitable outlet for the
sugar cane than raw sugar.
In Cambodia, the adaptation of the pig feeding system from sugar cane to sugar palm was
relatively straight- forward, as in each case the soluble carbohydrates in the juice were
a mixture of sucrose and the reducing sugars, glucose and fructose.
A pig producer is preparing pig feed by mixing sugar palm juice with
freshwater fish silage ...
Un �leveur de porcs pr�pare la p�t�e � base de jus de palmier � sucre et de poisson
d'eau douce ensil� ...
Un productor de cerdos est� preparando el pienso mezclando jugo de palma de az�car con
ensilado de pescado de agua dulce...
... which her husband is feeding to the pigs
... avec laquelle il nourrit les cochons
... que administra a los cerdos
An integrated farming system based around the sugar palm tree is an appropriate strategy for rural areas of Cambodia (Khieu Borin, 1996). Generally, in regions where sugar palms are found, each farmer owns at least ten sugar palm trees, which sets a limit on the scale of the livestock component. The juice from two palms (approximately 10 kg) contains sufficient digestible carbohydrate (about 15.4 MJ of digestible energy) to satisfy the daily needs of one pig averaging 50 kg live weight. Thus, ten palm trees per family can fatten five pigs. As in the case of sugar cane, there is virtually no protein in sugar palm juice, therefore some source of supplementary protein is needed. Traditional sources such as soybeans are not widely available in Cambodia and are expensive. The results summarized in Figure 2 were obtained in farm households (two pigs per family) where the protein supply was restricted to 150 g per day from soybeans with small amounts (about 500 g per day) of freshwater spinach (Ipomoea acuatica). The most important feature of this demonstration was that the farmers made more profit from feeding the palm juice to pigs than converting it into sugar when the fuelwood for juice concentration had to be purchased (Figure 3).
2
Average daily weight gain of pigs fed with sugar palm juice, and profit from rearing
Prise de poids journali�re moyenne des porcins aliment�s avec du jus de palmier � sucre
et rentabilit�
Aumento diario medio de peso de los cerdos alimentados con jugo de palma de az�car y su
rentabilidad
3
Comparative profit of different farmers from sugar palm trees used for sugar production or
for pig rearing
Profit comparatif tir� par les exploitants des palmiers � sucre utilis�s pour la
production de sucre ou pour l'�levage de porcs
Beneficios comparados de distintos agricultores a partir de las palmas de az�car
utilizadas para la producci�n de az�car o para la cr�a de cerdos
Another approach has been to use small waste fish commonly available from
Tonle Sap Lake during January and February which is the traditional fishing period when
the water flows out to the sea. During this period, small fish that are not suitable for
human consumption can be purchased for less than US$0.06 per kilogram but, because the
period when the small waste fish are available is short, they must be conserved. Ensiling
with palm syrup (10 percent) and rice bran (40 percent) is a simple procedure. After
removal of the intestinal tract, the fish are washed and placed in a bamboo basket for one
to two hours to drain. They are subsequently mixed with the palm syrup followed by the
rice bran and then sealed inside a polyethylene bag supported inside a ceramic container
or in a hole in the ground. After 14 days the silage is ready for feeding to the pigs but
it will remain in good condition for five to six months if anaerobic conditions are
maintained.
A more common practice is to dry the waste fish in the sun. A demonstration was carried
out in Samroung district, Takeo Province, with the participation of 15 farmers. The diet
was 6.5 kg of palm juice, 1 kg of rice bran, 300 g of dried fish (approximately 110 g of
protein), 5 g of salt and green vegetable according to availability. The average daily
weight gain was 420 g per pig with a range of 220 to 580 g (Figure 4).
4
Performance of pigs fed on sugar palm juice, rice bran and sun-dried fish
Engraissement des porcs nourris avec du jus de palmier � sucre, du son de riz et du
poisson s�ch� au soleil
Rendimiento de los cerdos alimentados con jugo de palma de az�car, salvado de arroz y
pescado secado al sol
The results of recent studies with the sugar palm in Cambodia have shown:
It is recommended that research be directed towards:
Davis, T.A. & Johnson, D.V. 1988. Current utilization and
further development of the Palmyra palm (Borassus flabellifer L., Aracaceae) in
Tamil Nadu State, India. Econ. Bot., 41(2): 23-44.
FAO. 1983. The Palmyra palm: potential and perspectives. By A. Kovoor. FAO
Plant Production and Protection Paper No. 52. Rome.
Khieu Borin. 1996. The sugar palm tree as the basis of integrated farming systems
in Cambodia.Contribution to Second FAO Electronic Conference on Tropical Feeds. Livestock
Feed Resources within Integrated Farming Systems.
Khieu Borin & Preston, T.R. 1995. Conserving biodiversity and the environment
and improving the well-being of poor farmers in Cambodia by promoting pig feeding systems
using the juice of the sugar palm tree (Borassus flabellifer). Livestock
Research for Rural Development, (7)2: 25-30.
Khieu Borin, Preston, T.R. & Lindberg, J.E. 1996. Juice production from the
sugar palm tree (Borassus flabellifer) in Cambodia and performance of growing pigs
fed sugar palm juice. In Sustainable Tropical Animal System, p. 1-11. Swedish
University of Agricultural Sciences, Uppsala, Sweden. (M.Sc. thesis)
Mena, A, Elliot, R. & Preston, T.R. 1981. Sugar cane juice as an energy source
for fattening pigs. Tropical Animal Production, 6(4): 338-344.
Morton, J.F. 1988. Notes on distribution, propagation, and products of Borassus
palms (Arecaceae). Econ. Bot., 42(3): 420-441.
Preston, T.R. & Leng, R.A. 1987. Matching ruminant production systems with
available local resources in the tropics and subtropics, p. 1-5. Armidale, New South
Wales, Australia. PENAMBUL Books Ltd.
Preston, T.R., MacLeod, N.A, Lassota, L., Willis, M.B. & Vel�zquez, M. 1998.
Sugar cane products as energy source for pigs. Nature, 219: 727.
Sarria, P., Solano, A. & Preston, T.R. 1990. Utilizaci�n de jugo de ca�a y
cachaza panelera en la alimentaci�n de cerdos. Livestock Research for Rural
Development, 2(2): 92-100.