The role of livestock in integrated farming systems in the tropics

T R Preston

Finca Ecológica, University of Agriculture and Forestry
Ho Chi Minh City, Vietnam

Abstract

The role of livestock in farming systems has changed dramatically in the last 50 years as they have become increasingly competitive rather than complementary with humans. Production systems have become specialized enterprises dependent on purchased feeds, often with no associated cropland area for feed production or to receive the manure. The ready availability of cheap oil has facilitated the use of agro-chemicals and husbandry practices, including crop rotations, forage crops for animals, and use of manure as fertilizer, have ceased to be a prerequisite for profitable farming.

Diminishing oil reserves and global warming will eventually mean higher prices for fossil fuels. Solar energy is the only sustainable alternative and livestock will play a vital role in enhancing the use of this resource but with primary emphasis being on their capacity as recycling agents rather than as primary converters of plant biomass into animal protein.

Present methodologies for evaluating livestock-based activities are not suitable when the output is multi-faceted and has implications for the environment. Input-output coefficients have to be applied to the whole system and not just the animal. Changes in soil fertility should be assessed and this can be related to effects on crop yields.

The challenges are for the technologist to develop more efficient systems for deriving benefit from solar energy using an holistic approach; and for the economist to determine in monetary terms the presently intangible cost of pollution and the income to society of activities that enhance, rather than destroy, the environment.

Key words: Livestock, integrated farming, biomass, multi-purpose, recycling

Livestock and economic development
The role of livestock in farming systems has changed dramatically in the last 50 years and while overall numbers have increased faster then the human population, livestock have become increasingly competitive rather than complementary with humans. This is because milk and beef production have become specialized enterprises dependent on purchased feeds, and often in the case of poultry, pigs and beef cattle, with no associated cropland area for feed production or to receive the manure.

These developments have been facilitated by the ready availability of cheap oil which led to cheap agro-chemicals. Good husbandry, which included crop rotations, forage crops for animals, and use of manure as fertilizer, was no longer a prerequisite for profitable farming. First coal, then oil, fueled the industrial revolution and urbanization, leading to profound changes in the ratio of food producers to food consumers. Import of food from agricultural to industrial countries was the first form of food security and, stimulated by two world wars, was followed by movements for self-sufficiency achieved in the industrial countries by massive subsidies made possible by access to cheap fossil fuel.

A return to integrated agriculture and ruralization will only be possible when the sun again becomes the dominant energy source. Diminishing oil reserves eventually means increasing costs of extraction therefore higher prices (there are signs that this is already happening). Recognition that the rate of global warming is increasing will ultimately lead to pressure to curb burning of fossil fuels.

Livestock and fossil fuel
The role of livestock in farming is directly related to the degree of utilization of fossil fuel energy. Cheap fossil fuel has changed the primary role of livestock from the recycling of plant nutrients to specialized production of meat and milk. As the world reverts to solar energy so the role of livestock will also change with efficient recycling being the priority instead of inefficient transformation of feed into animal products.

The task of the “new” professional must be to prepare for these opportunities. The “old” professionals wedded to disciplines, commodities and specialization may not yet be ready to change, viewing this shift of emphasis as turning back of the clock. The “new” professional will see the opportunities inherent in the application of new knowledge to solar-based agriculture and will respond to the challenge of feeding and providing energy and shelter to 10 billion people using only natural renewable resources.

A glance at the global energy flows shows us that this is possible (Table 1). The energy from the sun that reaches the earth annually is one hundred time greater than the total proven reserves of fossil fuel; while newly formed biomass exceeds by a factor of ten the annual usage rate of fossil fuel.

Table 1: Annual flows of energy from the sun and conversion into biomass and food compared with fossil fuel reserves and usage rate (Hall D O and Rosillo-Calle F 1991)

Use of solar energy to feed the world's population is more efficient when plant products are consumed directly rather than after “upgrading” by livestock. From the point of human health, especially in the industrial world, there will be benefits from reducing the proportion of the diet in the form of animal products. This does not mean that livestock will no longer be necessary. On the contrary, they will be even more important but in a changed and synergistic role. They will increasingly be seen as efficient “recycling” agents rather than inefficient “converters”.

Strategy for efficient natural resource management for food, feed, fuel, and shelter
Population pressure for food, fuel, shelter and environmental rehabilitation sets the stage for the following steps in the strategy for natural resource management:

• Maximization of solar energy capture into biomass easily fractionated into multiple end uses
• Promotion of cropping systems which simulate the local natural ecosystem. In the humid tropics this means multi-strata vegetation in which trees and shrubs predominate.
• Efficient use of the end products for food, fuel, shelter and environment enhancement

The first two elements in the strategy will change the nature of the products available for livestock production. The earlier discussion in this conference highlighted the opportunities of a new resource - the sugar palm - not previously considered as a source of animal feed. Water plants and leaves of trees are other new feed resources that are now receiving increased attention.

Identification and new uses of sugar cane in integrated farming systems for livestock (Preston 1988) and energy (Alexander 1985) marked earlier attempts to direct attention to efficient solar energy capture as the starting point for better management of natural resources. This opened the way to consideration of other plant species as has been highlighted in the discussion about the merits and alternative uses of the sugar and coconut palms. There will be many more alternatives especially in the tropics when we begin to look “up” instead of “down” in our search for efficient and productive sources of plant biomass.

Transforming efficiently the new forms of biomass into desirable end products requires at the outset a multi-disciplinary and multi-commodity approach. Energy is as important as food in securing an acceptable standard of living and complementarity rather than competitivity must be the basis of the strategy.

Thus it makes no sense to derive power alcohol from potentially fermentable carbohydrate if this resource can be used as food. Equally the combustion of organic (high moisture) household waste to provide energy is unacceptable. Lignified plant residues are more appropriately converted to fuel (by gasification) than into livestock feed which requires expensive physical and/or chemical manipulation. All livestock and human excreta should pass first through biodigesters before being recycled as fertilizer.

Many of the technologies to promote more rational end use of the earth's natural resources already exist. What is lacking is political will and economic incentives.

Livestock in integrated farming systems

In a later paper in this conference (Rodriguez and Preston 1996), we have stressed the advantages of indigenous breeds of livestock when multi-purpose “recycling + upgrading” replace “specialized feed conversion” as the major role of animals in natural resource management. There are many opportunities to be investigated. Certainly the animal provides the most efficient pre-treatment of high-moisture biomass to convert it to a substrate suitable for biodigestion. Equally the “animalbiodigester” sub-system is a more efficient way of preparing organic matter for return to the soil than aerobic composting.

In such systems the criteria for the ‘efficient’ animal should give greater weight to traits such as the capacity to select and consume voluminous and usually fibrous materials rather than digestibility. Milk and meat will be by-products rather than primary outputs in these scenarios.

Thus as emphasis has shifted from “adapting the resource to the system” (eg: the maize-soya bean feeding system for pigs) to “adapting the animal to the resource” (Preston and Leng 1987), the economic traits required of livestock will also change. This will be particularly true for the tropical regions. The advantages in the tropics of dual purpose (milk-beef) breeds and management systems over specialized milk and beef production as separate enterprises are increasingly being recognised at least in tropical Latin America (Preston and Murgueitio 1994). Incorporation of work, for land cultivation and transport as a third purpose, and of fuel (biogas) + fertilizer as a fourth purpose is perhaps too demanding on needs for nutrients. However, multi-purpose work plus fuel/fertilizer plus meat is a traditional way of using cattle and buffaloes in SE Asia and is a more efficient way of using fibrous crop residues than specialist (ranching) production of meat alone.

Table 2: Gross income from one ha of sugar cane producing 80 tonnes of stalks/ha/year (Preston T R 1996, unpublished data)

# Assumes the result when applied to soil is stalk yield increase of 10 tonnes/ha at USD38/tonne (from *+**)
## 8 tonnes dry matter @USD100/tonne
### Factory price of USD20/tonne
* 8 tonnes of digestible dry matter @USD200/tonne
** Producer gas equivalent to 4,800 litres diesel fuel @USD0.30/litre
(?) Unknown negative effect due to atmospheric pollution

Evaluating the role of livestock in integrated farming systems
Our present methodologies for evaluating livestock-based activities are not suitable when the output is multi-faceted and has implications for the environment. Input-output coefficients have to be applied to the whole system and not just the animal. One approach is to make some measure of total solar energy capture in the system including that returned to the soil. Soil organic matter should be monitored as organic matter is a nutrient (source of energy) for soil organisms. Changes in soil fertility should be assessed and this can be related to effects on crop yields. The increases in annual yield of sugar cane of 10 tonnes/ha reported by Mui et al (1996) can be attributed mainly to increases in soil organic matter through return of dead sugar cane leaves to the soil.

It would be desirable also to have some means of assessing changes in the flux of methane to the atmosphere which will be increased when ruminant animal components of the system are increased and will be reduced by processing livestock and human excreta through biodigesters and by improvements in soil fertility. It seems that soil organic matter may be an important source of energy for organisms that oxidize methane (Keller et al 1990; Mosier et al 1991).

The data in Table 2 are an example of the type of analysis that should be applied when assessing the value of sugar cane managed conventionally for industrial sugar or by fractionation for feed and fuel

Gross income is tripled when the products of sugar cane are used in a diversified way rather than solely for production of sucrose. If the add-on value of the livestock products are also includedmilk, meat, manure for fuel (biogas) and fertilizer (biodigester effluent) - then the contribution to human needs and the environment is vastly increased as is the total income to the farmer.

There are many new opportunities for livestock in integrated farming systems. The challenges are for the technologist to develop more efficient systems for deriving benefit from so'ar energy using an holistic approach; and for the economist to determine in monetary terms the presently intangible cost of pollution and the income to society of activities that enhance, rather than destroy, the environment

References

Alexander A G 1985 The energy cane alternative Elsevier:Amsterdam pp1–509

Hall D O and Rosillo-Calle F 1991 Why biomass matters: Energy and the environment. Network News Volume 5, Number 4 pp 4–15 (Biomass Users Network)

Keller M, Mitre M E and Stallard R F 1990 Consumption of atmospheric methane in soils of central Panama; effects of agricultural development. Global Biogeochemical Cycles 4: 21–27.

Mosier A, Schimel D, Valentine D, Bronson K and Parton W 1991 Methane and nitrous oxide fluxes in native, fertilized and cultivated grasslands. Nature 350: 330–332.

Nguyen Thi Mui, Preston T R, Dinh van Binh, Le Viet Ly and Ohlsson I 1996 Effect of management practices on yield and quality of sugar cane and on soil fertility. Livestock Research for Rural Development. Volume 8, Number 3: 51–60

Preston T R 1988 Fractionation of sugar cane for feed and fuel. In: FAO Expert Consultation on Sugarcane as Feed (Editors: R Sansoucy, G Aarts and T R Preston) FAO:Rome pp310–319

Preston T R and Leng R A 1987 Matching Ruminant Production Systems with Available Resources in the Tropics and Subtropics. PENAMBUL Books Ltd: Armidale NSW, Australia

Preston T R and Murgueitio E 1992 Strategy for sustainable livestock production in the tropics CONDRIT Ltda: Cal: pp89.

Rodriguez Lylian and Preston T R 1996 Indigenous breeds and local feed resources: fundamental issues in integrated farming systems. In: Sustainable livestock production on local feed resources (Editor: T R Preston). Proceedings of National Seminar Workshop. 10–14 September 1996. University of Agriculture and Forestry, Ho Chi Minh City