Lylian Rodríguez and T R Preston
Finca Ecologica, University of Tropical Agriculture, Thu Duc,
Ho Chi Minh City, Vietnam
The tropics present great opportunities for sustainable development thanks to the
enormous cultural and biological riches of these regions. The rational exploitation of
local feeds and local breeds of livestock will support much more sustainable production
systems in the medium and long term. These have received insufficient attention in the
past and have not been considered seriously because of the introduction of
"exotic" systems based on high inputs, high technology and "breeds of high
genetic merit". As a result, local breeds of pigs and cattle in many tropical
countries have disappeared or their population is decreasing drastically.
On-farm research has shown that small scale farmers in Vietnam and in many parts of the
tropical world continue to work with local breeds because of their good adaptation to the
prevailing conditions. A project was carried out in two villages in a rainfed hilly region
in Central Vietnam, involving the use of local Mong Cai pigs, local feeds supplemented
with duckweed, and plastic biodigesters to produce energy for cooking and the
nitrogen-rich effluent as fertilizer for the ponds in which the aquatic plants were grown.
A study of the nutrition of Mong Cai, Large White and crossbred pigs showed that the
indigenous breed would eat greater quantities of duckweed and use it more efficiently than
the exotic breed. Local sows fed duckweed were also more prolific than exotic breeds on
small farms with feed resources of low nutrient density.
The studies were carried out with a participatory approach which identified the
importance of the local pigs and feed resources and the enthusiastic adoption of the
biodigester technology and the production of duckweed based on the fertilized ponds. The
priorities of the farmers were identified and a proposed intervention based on restricted
milking of local cattle abandoned because it was considered too long term. Parallel
studies in Cambodia led to the development of pig feeding based on juice from the sugar
palm (Borassus flabillifer) supplemented with boiled soya bean seed and water
spinach. Biodigesters were also integrated into the farming system.
The various studies demonstrate that the appropriate use of local feed resources and
indigenous livestock breeds requires close integration between crops and livestock within
the system. The excreta is recycled on the farm to produce energy and the effluent is used
for fertilizer to produce protein supplements for the livestock.
There is a growing disparity between the expanding world population and the earth's
food producing capacity, the rate of increase of which is less than the rate of population
growth. As a result, food supplies per capita are decreasing (Brown and Kane 1994).
However, an important issue here is the role of livestock. As living standards rise, so
does consumption of livestock products. But the feeding systems to produce these products,
especially in the industrial countries, use the same feed resources as are eaten by
humans, namely cereal grains and soya bean meal. It is estimated that almost 50 % of the
world grain supply is consumed by livestock (FAO 1993). It has been argued (Preston 1995)
that if all the world's grain production was reserved for human consumption then there
would be enough to feed the 10 billion inhabitants at which point the world population is
expected to stabilize.
The strategy that is proposed is that not only are there many alternatives to cereal
grains as the basis of feeding systems for livestock production but that many of these
systems result in a more efficient and sustainable use of natural renewable resources. The
first step in this strategy is to recognize that the production of cereal grains for
livestock feed, as practised in the industrial countries, is not sustainable because it
depends on the inputs of massive amounts of energy derived almost exclusively from fossil
fuel. According to the data from Pretty (1995), the production of rice in the USA requires
that some 65% of the energy value of the rice is imported into the system in the form of
fossil fuel derived inputs. The energy need for maize is less (about 25%) but still
The examples of alternative energy-rich crops proposed by Preston (1995) include sugar
cane, cassava, sugar palm, oil palm and coconut palm. The yields of all these crops
expressed in terms of grain equivalent exceed what can be expected from cereal grains.
Moreover, many of them, for example the palm trees, can be grown in association with other
crops in multi-strata systems and are much less demanding in terms of energy inputs for
cultivation. The limitations of all these alternative crops, as sources of feed for
livestock, are in the imbalance of nutrients and specifically protein. On the other hand,
they are all low in fibre. In fact, the energy from sugar cane, and the palm trees (oil
and sugars) contains no fibre at all.
The feeding systems designed so far, using these new resources, have relied mainly on
conventional sources of protein such as soya beans, groundnuts and fish meals (Sarria et
al 1990; Ocampo 1994; Khieu Borin and Preston 1995). This is obviously a major constraint
as these conventional protein-rich meals are relatively low yielding and soya beans, which
is the major protein crop, are not well adapted for growing in the tropics where they
yield much less than when grown in sub-tropical regions.
Alternative sources of protein were also proposed by Preston (1995). These include the leaves of many trees and shrubs and several water plants as examples of truly tropical feed resources capable of very much higher protein yields than soya beans. The major nutritional limitation of these feed resources is that they are relatively high in fibre, especially the leaves and foliage from trees and shrubs, which puts a constraint on their digestibility, especially by monogastric animal species. Thus the characteristics of these alternative sources of energy and protein, when combined into feeding systems, can be summarized as follows:
These features have important implications for the design of livestock feeding systems. It means that:
All of these features favour the use of these feed resources in integrated farming systems where there is a close association between crops and livestock. Small scale producers who live on their farms will benefit more from these feeding systems than "corporate" farmers. There will be opportunities for self sufficiency in fuel (in the form of biogas) and fertilizers because of the ready availability and relatively larger amounts of manure. Local breeds and crossbreeds of local with improved strains are likely to have comparative advantages over "exotic" high performance genotypes.
It is evident from this analysis that the feeding and farming systems that need to be
developed in order to take advantage of the opportunities offered by these alternative
feed resources will be quite different from those currently practised in most industrial
countries. This in turn has implications for research, training and acquisition and
transfer of knowledge. Appropriate knowledge will rarely be found in the scientific
publications emanating from institutions in the "North". Farmers who over
generations have learned how to use the locally available resources will be more valuable
sources of information.
Similarly, appropriate germ plasm is more likely to be found in local ecosystems than
in the laboratories and experiment stations of the animal and plant breeders in the
industrial countries. There are many examples of situations where indigenous breeds and
local feed resources have proved to be more appropriate than exotic types and imported
technologies. Crossbred (F1) Holstein-Zebu cattle were more efficient producers of milk
and meat in a tropical environment in Brazil (Madalena 1989) and in Colombia (Rodriguez
and Cuellar 1994) than the purebred Holstein. Leaves from the Jackfruit tree (Artocarpus
heterophyllus) supported higher live weight gains in indigenous goats in Vietnam than
the more digestible foliage from Trichanthera gigantea (Keir et al 1997). Hybrid
broiler chickens quickly succumbed to disease and malnutrition when they were put in an
environment where "scavenging" local chickens were able to produce normally
(Preston T R 1995, unpublished observations).
A study was carried out in two villages (Binh Dien and Xuan Loc) in a rain-fed hilly
region in Central Vietnam (Rodriguez et al 1996). The areas were visited in 1994 and the
researcher lived in the villages during 1995. Discussions were held with the People's
Committee and the Women's Union to consider and develop the ideas. The priorities of the
farmers were identified and a proposed intervention based on restricted milking of local
cattle abandoned in the light of the insistence of the farmers that the expected benefits
were too long term and they had more immediate needs. The participatory approach
identified the importance of the local pigs and feed resources and the enthusiastic
support for the introduction of low-cost biodigesters and the production of duckweed in
ponds fertilized with the nitrogen-rich effluent.
As a result of the project activities in the village and farmer expectations, research
to document the local breeds became a priority. A survey was done to get some baseline
data. Local pigs proved more prolific than "exotic" breeds in the households of
poor farmers in these areas where available feed resources are of low nutrient density,
and especially low in protein (Nguyen Thi Loc et al 1997). The survey demonstrated a mean
weaning rate of 10.3 pigs per sow in Binh Dien and 9.59 in Xuan Loc. The farrowing
interval was 181 days. Mortality to weaning was less than 10%. These observations at
village level about the efficiency of the Mong Cai breed in the use of local resources
were the basis for carrying out an on-station experiment.
The Mong Cai pig of Vietnam appears to have comparative advantages over imported
"exotic" strains when the need is to be able to consume large quantities of a
voluminous feed such as duckweed (Rodriguez and Preston 1996). Nutritional studies were
carried out using a diet of sugar cane juice and duckweed (grown in ponds fertilized with
biodigester effluent) fed to local (Mong Cai) pigs, Large White pigs and crossbreds. The
purebred exotic (Large White) pigs failed to adapt to the use of duckweed and had to be
eliminated from the experiment. In that study, the nutritive value of duckweed was found
to be high when fed to indigenous pigs and their crosses. Half the pigs were able to
consume enough fresh duckweed to provide a diet with more than 10 per cent protein. This
local resource was not useful with the poorly adapted exotic breed.
The excreta produced by the pigs was a valuable resource that could be used in
low-cost, plastic biodigesters. The potential benefits of this technology were
enthusiastically received, especially by the women. It was calculated that at least 1000
tonnes of firewood were used annually to cook feed for pigs and 678 tonnes of firewood
used to cook food for the 364 households in Xuan Loc Village alone. As part of the project
activities, more than 50 biogas digesters were installed in Binh Dien and Xuan Loc
villages, with an average cost (for materials) of USD 29.00, including two burners. These
provided biogas for cooking of both human and pig food.
There was also a potential connection between the biodigesters (being installed primarily as a source of fuel) and the need to improve the diet of the pigs. Conventional protein supplements are only available in the market in Hue City and are expensive. The proposal was to grow duckweed in ponds fertilized by the nitrogen-rich effluent produced from the biodigesters. Duckweed can contain up to 40% protein in the dry matter when raised in this way (Leng et al 1995) and can be grown almost anywhere in the tropics where there is water. Farmers quickly learned to grow the plant and to keep it in good condition, and they also learned that it could be used as a high quality protein supplement not only for pigs, but also for ducks and chickens. Common ducks in Vietnam also appear to be able to eat greater quantities of this water plant than do "improved" Muscovy ducks (Bui Xuan Men et al 1996).
The combined development of the pig, biodigester and duckweed technologies led to an integrated approach which was adopted and refined by the farmers. However, a negative aspect of the project was that the original proposals to develop a milk programme with the local cattle were abandoned because it was not acceptable to the people and too many costs and constraints were anticipated.
The use of the sap (or juice) from the sugar palm tree (Borassus flabillifer) as feed for pigs is another excellent example of a technology developed from indigenous knowledge (Khieu Borin and Preston 1995). This tree grows wild in Asia from the Persian Gulf to the Cambodia-Vietnam border and is cultivated in India, Malaysia and other countries. It is used locally for sugar production from the inflorescence and many byproducts from other parts of the tree.
In the study cited above, the fresh juice was fed to crossbred (Yorkshire x Duroc x
Haiman) pigs in 14 farm households in a village in the Takeo province of Cambodia. Each
farmer had 6 pigs and access to at least 12 sugar palm trees; housing was constructed from
palm trunks with roofs thatched with palm leaves and solid concrete floors. Each farm had
a plastic biogas digester installed to utilize the effluent. The pig diet consisted of ad
libitum sugar palm juice, together with 400 g/day boiled whole soya bean seed with added
lime and salt and 500 g/day water spinach. Live weight gains ranged from 350-450 g/day.
More importantly, the system was more profitable than sugar production which needs much
more wood for concentrating the juice. The system was less labour-intensive and the pigs
produced manure which was transformed through biodigesters to effluent and used as
fertilizer for fish ponds, water plants or rice and fruit trees, with no harmful effects
on the environment.
The farming system must be fully integrated in order to optimize the use of locally available "alternative" resources. Strategies for sustainable livestock production in the tropics had been developed in Colombia and elsewhere (Preston and Murgueitio 1992). Integrated systems were originally based on sugar cane and its byproducts as the source of energy, with legume trees and water plants as sources of protein, for feeding pigs, ducks, sheep, goats and cattle.
The simple biodigester technology had been developed and refined at CIPAV and the
principle of using the effluent as a fertilizer for ponds and also in the production of
earthworms for compost and/or feed had also been applied. The results reported here
demonstrate that the basic model has many variants but the principles are the same. It is
important to identify local feed resources and the preferences of local people for
different types of livestock. In all cases, there should be minimum "waste" in
the system. By-products and residues originating in one component of the system become
inputs for another "productive" activity.
The beneficiaries from a strategy based on local resource use in integrated farming
systems are many. Women will benefit when there is close integration within the farming
system. Firewood, the collection and use of which is done by women, can be replaced by
biogas when livestock are confined and the biodigester will be more productive when local,
less digestible (by the animal) feed resources are used. The existence of
genotype-environment interactions will have commercial significance when local feed
resources are used. They have significance in other ways. They certainly contribute to
biodiversity and have positive effects on the environment. They give empowerment to
farmers who may be economically "poor" but who are "rich" in knowledge
of local resources.
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Received 1 May 1997
1. This paper was originally presented in the FAO Electronic Conference: Livestock feed resources within integrated farming systems (Moderators: Christophe Dalibard, Rene Sansoucy, Andrew Speedy). 1996/97 FAO: Rome
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