Livestock feeding systems and the environment
Rapid population growth, in a context of scarce material and
natural resources, is a common feature of developing countries. It is evident
that appropriate and sufficiently productive agricultural technologies are
needed urgently. Livestock production strategies and policies are needed which
make optimum use of local resources without inflicting further damage on
ecological environments already under pressure. However the role played by
livestock in the overall farming system has been largely ignored.
Whilst technological transfer involving primarily Western models
continues, research into the potential of regional resources is being neglected
and social and economic constraints hindering innovative techniques are not
being given adequate attention.
New livestock strategies are needed urgently; strategies which
do not create import dependence but rather stress local needs, local resources,
and identify the potential of indigenous breeds and feed resources.
Livestock and the greenhouse effect
It is generally agreed that the industrialised West has achieved
a high rate of livestock productivity by using a disproportionate amount of the
worlds resources, particularly fossil fuels, marine fisheries, and
protein-rich cakes and meals. The efficient animal industries of industrialised
countries would have been much less productive if their access to inputs,
derived from fossil fuels, were as limited as those of the worlds poorer
countries. Fossil fuels are too expensive for developing countries struggling
with limited foreign exchange. Alternative and renewable energy sources have to
Industrial countries are becoming increasingly aware of the
environmental threat posed by fossil fuels and they are beginning to look for
less destructive industrial and agricultural technologies. Rising world
temperatures are causing growing concern and an awareness of the
greenhouse effect is spreading. This is seen as a consequence of
increases in levels of carbon dioxide, methane, CFCs and oxides of nitrogen.
Carbon dioxide and methane are intimately related to plant growth and animal
production. Methane contributes to heat retention in the earths atmosphere
and reacts destructively with the ozone layer.
Herbivorous animals mainly cattle and buffalo, contribute 15-25%
of the total global production of methane. With this in mind research priority
has to be given to developing feeds for monogastric animals that can be derived
from local tropical biomass such as sugar cane, water plants, and forage trees.
These feeds use a minimum of fossil fuels and produce negligible quantities of
The methane production factor in herbivorous animals means that
ruminants must be given supplements to ensure efficient fermentative digestion.
Research is also necessary for a better understanding of factors involved in the
accumulation of CO2 and CH4 in the atmosphere. Agricultural development
strategies at national and global level must aim at a reduction and eventual
stabilisation of the principal greenhouse gases.
Planning livestock development programmes is critical and
requires interdisciplinary cooperation. Action has to take place simultaneously
on several fronts. Health, feeding, breeding and socio-economic aspects must all
be considered and livestock and crop production must complement each other
The potential of lesser known species, micro-livestock and
wildlife has to be explored and livestock production techniques must be selected
which optimise long- and short-term benefits. In developing countries, Multiple
Ovulation and Embryonic Transfer (MOET) and animal importation are likely to be
less cost effective tools than artificial insemination (AI). AI can ensure
genetic improvement and can be used as part of an integrated programme aimed at
upgrading calving percentages and increasing survival rates in local herds.
Local legislation can play an important role in ensuring the quality of inputs
(vaccine and semen) and in setting realistic standards for local products such
as meat and milk. Local legislation can also be used to ensure the supply of
such valuable inputs as seeds and scientific information.
Research is essential to the future of livestock production in
developing countries and one important issue is how to make the best use of
animals for draught at the smallholder level. Research is needed on genetic
improvement programmes for multi-purpose traits. Studies are needed into animal
partition nutrients for work, foetal growth, lactation and the effects of
reproduction. Finding the best feeding progammes for adaptation to available
local resources are also areas requiring investigation.
The use of local feed resources
The question of feed resources is central and raises the issue
of dependence on imported food, feeds and technological inputs. It is important
that livestock feeding systems use locally available feed resources. These
include feeds which can be produced using alternative cropping systems. Emphasis
must be given to management systems and especially to the role supplementary
feeding plays in optimising the use made of local resources.
A major problem arises in how to evaluate and use local feeds.
Two categories are useful in identifying feed resources. First there are those
basal feeds which provide the bulk of the diet and secondly there are those
feeds which are high in nutritional content and which can be used as potential
Basal feeds should be allocated according to digestive
requirements: fermentation (feeds rich in cell wall components such as crop
residues, agro-industrial by-products and pasture) or intestinal gastric
enzymes (sugars and starches such as those found in molasses sugar cane
juice, and cereal grains). Supplements are recommended where nutritional
deficiencies are likely in basal feeds. These supplements would usually be high
in protein, examples being the vegetable protein meals from the oil seed
industry, animal protein meals forage trees? shrubs and water plants.
The question of the chemical analyses needed in the initial
formulation of diets based on these components is relevant here. Where pigs and
poultry are concerned. important factors include protein elements, amino acid
content, potential toxic compounds, such as fungal toxins for example and
secondary plant components. Digestibility has also to be considered. In
preparing ruminant diets attention has to be paid to soluble nitrogen, insoluble
protein, rumen degradability, and the efficiency of the rumen ecosystem in
relation to a particular feed. Attention must also be given to the rumen ammonia
concentrations in animals fed basal diets. In the supplements fed to pigs and
poultry, protein and amino acid content, secondary plant components and toxins
should be carefully examined. The digestibility of the protein must also be
considered. Where ruminant supplements are concerned, the important factors are
insoluble protein and digestibility.
In general, it is useful if response curves can be established
showing the relationship between levels of animal performance and the amount of
the most limiting supplement added to the basal diet. This limiting supplement
is frequently either an important or an expensive and/or scarce item. The
results of such research will provide essential biological and economic data for
future decision making.
Given the high cost of imported cereal grains, research must
concentrate on finding an efficient and more cost effective way of using grain.
In poultry diets this can be done by using a choice feeding system where whole
grain, pelleted protein concentrates and a particle source of calcium carbonate
are offered in the same trough. Restricted feeding of grain can be complemented
by scavenging for protein and the productivity of free range village birds can
be improved by giving strategic supplements.
More effective ways will have to be found of making use of
alternative feeds based on sugar derived from molasses, sugar cane juices and
starch derived from tubers, bananas, and plantains. More appropriate management
systems must also be devised for liquid and semi-solid diets and further
developments are needed in methods of satisfying amino acid requirements. Since
many alternative diets contain no fibre, studies are also needed into the role
of fibre. The question also arises of how best to exploit new sources of protein
from trees, shrubs and water plants. Combinations of protein sources which form
mixtures of high biological value (vegetable and animal protein) have to be
identified, and promising new sources of animal protein, rich in lysine and
methionine/cystine, such as earthworms and snails, must be evaluated.
Research in ruminant husbandry should stress the importance of
optimising the efficiency of rumen fermentative digestion by maximising the rate
of digestibility of fibre and ensuring adequate levels of rumen ammonia.
Research is needed to develop response relationships to by-pass protein (locally
available) before and after treatment, in order to increase by-pass
characteristics. Research must also be done on ways of protecting soluble
protein from being degraded in the rumen.
The strategic position of on-farm research must also be
emphasised in relation to feed resources. Once knowledge has been accumulated,
the quick est way to improve existing techniques is by on-farm experiments. An
example of this might be substituting concentrates typical of the present
feeding system for strategic supplements (ruminants) or alternative sources of
farm produced carbohydrates (pigs and poultry). Their effects can
then be monitored.
It is acknowledged that pasture and the role of livestock
management require particular attention, especially where problems arise because
land has been used too intensively in livestock production. If pasture use on
limited land areas is to be intensified, the problem of dry season feed scarcity
has to be overcome. Strategies which can make feed available during this period
will have a great impact on animal productivity. Establishing banks
providing fermentable big-mass, such as sugar cane, and both fermentable
nitrogen and by-pass protein, in the form of forage shrubs and trees, is highly
The possibility of increasing wet season grassland productivity
by introducing improved methods of species fertilisation should not be ignored.
This would have to be complemented by practices which could ensure the
continuity of feed supply during the dry season. Strategic nutrient packages
molasses/urea blocks and pelleted by-pass protein could be used as dry season
feed. These initiatives would result in a greater degree of self reliance and a
reduction in dependence on supplements coming from outside the region.
Finally, a word about erosion. Erosion is recognised as an
extremely serious consequence of overgrazing and several measures to combat it
are available. These include removing ruminants from areas where erosion is
taking place, and establishing land rehabilitation systems based on planting
multi-purpose trees. Permanent stable grassland can be encouraged by actively
discouraging tree clearing or tree harvesting unless there are tree reclamation
or tree re-planting programmes. Finally, where overgrazing threatens, greater
use must be made of full or semi-confinement management systems for all classes