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Overview of needs and justification for use of roots, tubers, plantains and bananas in animal feeding

Roots, tubers, plantains and bananas in animal feeding

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Over the past twenty years many developing countries have experienced
considerable difficulties in providing sufficient food to satisfy the ever
increasing demands of expanding populations.

In order to meet these needs they have looked to transfer technology
from developed countries. Often this technology has been developed for
temperate rather than the tropical or subtropical environments common
to most developing countries. Due to the close environments interaction
between crops and their environment only certain aspects of temperate
technology could be utilized. For this reason cropping systems that were
developed had to be designed for each environment in order to function
at all. However, in the case of livestock, which are less environmentally
sensitive, it was possible to transfer not only technology but whole
systems, including animals, building designs and feeds.

Many of the developing countries that followed this approach to
resolving livestock production deficits were able to finance such activities
through the export of primary products, such as oil, minerals, tea coffee,
etc., or by borrowing.

Over the last decade the above practice has commonly proved to be
financially unsustainable due to:

  1. escalating demands for livestock products, from expanding and
    increasingly urbanised populations, outstripping the amount of
    foreign exchange available to purchase the necessary inputs.

  2. reduced amounts of foreign exchange available for continued
    importation caused by falling earnings from the export of many
    primary products and the need to allocate greater amounts of
    foreign exchange to finance earlier borrowings.

For the above reasons FAO has on various occasions been requested by
developing countries to assist in seeking effective means of resolving
these problems. This expert consultation constitutes part of the initiative
to try to resolve this problem.


The use of cereals for animal feeding in developing countries was
recently considered at the meeting of the Intergovernmental Group on
Grains (IGG), held in FAO, Rome in November 1990 (FAO, 1990). The
report prepared for this meeting showed (Table 1) that of the total of 900
million tons of compound feed, in grain equivalents, used worldwide in
1988, around 280 million tons were used in developing countries (grain
equivalent refers to the feed value of 1 kg of barley in terms of
metabolisable energy and protein). Of this total more than half (149
million tons) consisted of cereals, including 127 million tons of coarse
grains, 12 million tons of wheat and surprisingly 10 million tons of
milled rice.

TABLE 1.Estimated World utilization
of livestock feed in grain equivalents
  World Developing countries
Output Growth rate Output Growth rates
1988 1971–80 1981–88 1988 1971–80 1981–88
(m.tons) (percent/year) (m.tons) (percent/year)
Concentrates 900 2.4 1.8 279 5.8 3.3
Cereals* 623 2.4 1.1 149 7.1 2.8
Oil meals* * 119 4.8 3.3 36 4.7 4.0
Brans & by-products 110 2.3 2.1 74 3.7 2.8
Roots & tubers 32 -0.5 2.4 17 2.9 3.9
Pulses 17 -1.3 12.3 3 1.4 1.9

Source: FAO 1990.

The IGG meeting also assessed the international trade in animal feed.
The briefing report showed that whilst developing countries were net
exporters of grains (approximately 5 million tons) in the early 1970s they
had become net importers by 1988 to the extent of about 21 million tons.
It is also of particular interest to note that estimates indicate that between
75 and 80 percent of all shipments to developing countries are cereals
used for animal feed production.

The replacement of these imports by local alternatives would enable
developing countries to save considerable foreign exchange, which would
otherwise have been needed to purchase the imported material, as well
as pay related shipping and transport charges. At the same time, the
development of local industries to produce substitutes for imported
feedstuffs could stimulate local industrial activity and help increase local
employment opportunities.


It is predicted that the population of the world will rise to around 6.25
billion from a current estimate of 5.29 billion by the year 2000 (Table 2).
As a consequence the world population will have doubled from that of
1960. Clearly more feed of every type will be required. The current
systems of feed production seem to be largely unsustainable and in
particularly those associated with the production of animal protein. The
clearance of forests to produce land to graze animals, overgrazing of
these and existing lands, together with methane and carbon dioxide
produced by such activities are currently believed to be implicated in
world environmental problems. It is therefore clear that more appropriate
and sustainable systems of livestock production and feeding will need to
be developed to meet both the current needs and future expansion.

World per capita protein production estimates are shown in Table 3.
These show that total protein supplies in developing countries (57.6g in 1983) were around half those of developed countries (99.2g in 1983), of
which approximately 20% was animal protein in developing countries but
50% in developed countries.

TABLE 2. World Population Growth by
Decade, 1950–90, with Projection to 2000.
Year Population (billions) Increase by decade (millions) Average annual increase (millions)
1950 2.515    
1960 3.019 504 50
1970 3.698 679 68
1980 4.450 752 75
1990 5.292 842 84
2000 6.251 959 96

Source: United Nations, Department of International Economics & Social Affairs, World Population
Prospects 1988 (New York: 1989)

There is considerable discussion amongst human nutritionists and
dieticians on the need to include protein of animal origin in human diets.
It is however clear that animal protein is generally more digestible that
plant protein, the amino acid balance of the animal protein more closely
matches human requirements, other essential nutrients are more common
in such products such as iron, calcium, phosphorus, etc. and there are
generally less toxicological problems associated with the use of animal
products. For these reasons, it is generally easier to obtain a balanced
wholesome diet, where animal proteins provide a significant proportion
of the total protein consumed.

Reference to Tables 3 and 4 indicates that in theory the amount of total
protein available in developing countries should be sufficient to meet the
overall populations needs. For this statement to be true it must be
assumed that the protein is distributed according to the need and that the
protein available is of adequate quality. Table 4 was prepared to indicate
the total and variation in protein need by humans of varying age and sex.
It is also particularly pertinent to note that the “Safe level of Protein
Intake” referred to is based on protein having the quality and digestibil-

TABLE 3. Per Capita Supplies of Total
and Animal Protein (in grams per day)
    Total Protein Total Animal Protein of which from
Meat Milk Fish Eggs
World 1971–73 65.1 21.5 10.0 6.6 3.3 1.6
1981–83 68.3 23.1 10.9 6.8 3.7 1.7
Developing 1971–73 52.7 9.2 4.1 2.5 2.1 0.5
Countries 1981–83 57.6 11.3 5.1 3.1 2.3 0.8
Developed 1971–73 96.0 52.3 24.6 16.8 6.8 4.1
Countries 1981–83 99.2 56.8 27.3 17.4 7.7 4.4

Source: FAO Economic and Social Development Paper, No. 80, aspects of the world feed-livestock
economy; Structural changes, prospects and issues (Rome, 1989)

TABLE 4.Example of Safe Protein
Intake for a Family Group of Varying Age and Weight
Family Group Member Age (yrs) Weight (kg) Safe Level of Protein Intake (g/day)*
Grandfather 60+ 65 49
Grandmother 60+ 50 37.5
Male 30–60 70 52.5
Female 30–60 55 41
Female (non pregnant) 18–30 55 41
” (pregnant) 18–30 55+ 47
” (lactating) 18–30 55+ 58.5
Male 14–16 55.5 52
Female 14–16 52 46
Male 10–12 34.5 34
Female 10–12 36 36
Male/Female 3–5 16.5 17.5
Baby under 1 7–10 14

Source: Data extracted from: Energy and Protein Requirements, Report of a Joint FAO/WHO/UNU
Expert Consultation, Technical Report Series, No. 724, World Health Organization, Geneva, 1985
ity of milk or egg. In practice it is likely that many of the most vulnerable
members of societies in developing countries will be receiving the
minimum (or less) quantity of protein and this will be mostly of vegetable
origin. For this reason it is likely that a large proportion of such societies
will be receiving diets deficient in many of the essential nutrients of
proteinaceous origin.

It would therefore appear that increasing the production and availability
of animal protein in developing countries is of significant importance if
the human populations of such countries are to be adequately fed.


There is a range of measures that developing countries can implement in
order to alleviate the above mentioned problem. These include:

  1. Maximizing the efficiency of current livestock production systems
    so that all existing resources, including human skills, animals,
    livestock facilities and feeds are used as efficiently as possible.

  2. Establishing what agro-industrial byproducts, that could be used in
    animal feeding in a country, are currently either unused or used
    inefficiently and if their use is economically viable use these to
    replace imported or human feeds.

  3. Developing local crops that can be grown to supply the nutrients
    currently obtained from imports or feeds that might be better used
    by humans.

The particular materials to be considered in this consultation clearly fall
into the latter two categories, though all points should be considered in
resolving the overall problem. In particular, the first measure listed above
is particularly relevant to the application of the last two. Even in
developed countries with well established traditions of byproduct
utilization the value of “wastes” (byproducts) or non-traditional feedstuffs
has till very recently been disdainfully undervalued. In many such
countries this view has now been replaced with an appreciation of their
true worth, to such a point, that the profitability of many livestock
industries now depends on the use of feeds largely consisting of
byproducts. This change in the traditional approach to livestock feeding
has now led to a more commercial approach to nutrient supply, involving
the use of crops on the basis of the yields of total nutrients per unit of
land and the cost of production of each nutrient. On this basis alone this
should result in the utilization of less cereal and more root and tuber
crops in many traditionally cereal producing areas (it is of interest to note
that the Netherlands are currently using less than 15% cereal in its feed

It is therefore quite clear that wholesale transfer of livestock systems
from dissimilar environments is not likely to be either the most economically,
nor productively efficient. Most situations, even at individual farm
level, are sufficiently different to merit the development of individually
designed systems, taking into account local factors and applying
fundamental scientific and economic principles.


Cereals generally make up between fifty-five and eighty-five percent of
most conventional compounded animal feeds, where they supply a major
part of the nutrients provided. Tables 5 and 6 respectively, show a range
of compositions for the most commonly produced feeds and cereals.
From these it is possible to see that cereals, used at the levels indicated
above, will provide not only the main part of the energy in feeds, but a
significant part of the total protein, together with minerals and vitamins.

Proteins and essential fatty acids are generally supplied from oilseed
cakes and meals and animal and fish protein products, many of which
originate from the regions of the world in which most developing nations
are located. Developing countries are in fact net exporters of these
materials. Over the last two decades these exports expanded at the rate
of 6.8 percent a year to reach a level of 29 million tons in the late 1980s.

Considering the above points it would appear that replacement of the
cereal component of feeds is likely to offer a beneficial first step towards
alleviating animal feed supply problems. The second step should then be
to increase the supply of feedstuffs so that animal production can be
increased and greater amounts of meat and livestock products made
available to all.

TABLE 5.Compositions of a range of
typical compounded animal feed
Feed Protein % Energy MJ/kg* Oil % Fibre % Calcium % Phosphorus %
Broiler Starter 23.0 12.7 3.0 3.0 1.0 0.7
Broiler Finisher 19.0 13.1 3.0 3.0 1.0 0.6
Layer 17.0 11.7 2.0 3.0 3.5 0.6
Pig Breeder 15.0 12.7 3.0 5.0 0.8 0.6
Pig Fattener 16.0 13.0 3.0 3.0 0.8 0.6
Calf Rearer 15.0 11.0 2.0 6.0 1.0 0.7
Dairy Cow 15.0 10.7 2.0 8.0 1.0 0.6

TABLE 6.Composition of a range of
cereal grains used in animal feed production
Cereal Protein % Energy MJ/kg* Oil % Fibre % Calcium % Phosphorus %
Maize 9.0 14.2 4.0 3.0 0.02 0.25
Millet 11.0 12.5 3.5 8.0 0.03 0.30
Sorghum 10.0 13.8 3.0 2.5 0.04 0.25
Rice (rough) 8.0 11.2 1.5 9.0 0.10 0.32
Wheat 11.0 13.0 2.0 3.0 0.05 0.35

TABLE 7.Composition of a range of
root, tuber, plantain and banana products (dry matters)
Product DM* % Protein % Energy * *
Oil % Fibre % Calcium % Phosphorus %
Cassava Root (whole) 36.2 2.8 14.0 0.7 1.6 0.1 0.02
Cassava Leaf 17.8 25.4 9.9 3.7 10.2 1.5 2.4
Sweet Potato Root (whole) 59.0 5.2 13.5 1.2 2.6 0.2 0.2
Sweet Potato 10.8 19.4 5.8 3.6 12.6 1.8 0.2
Leaf     (10.0)        
Plantain Fruit (mature) 29.4 4.0 14.5 0.8 1.1 0.8 0.3
Banana Fruit (ripe) 31.0 5.4 15.2 0.9 2.2 0.2 0.1
Banana/Plantain 16.0 6.4 3.5 0.8 23.7 0.9 0.3
Plant     (9.9)        

The plant materials identified for particular consideration in this
consultation, to replace cereals, are listed in table 7. This table also
includes an example range of compositions of primary raw materials that
may be derived from these plants. A comparison of the compositions of
the cereals and the possible substitutes being considered here produces
the following conclusions:

  1. That, on the basis of their composition alone, the roots, tubers and
    fruits of plants being considered here would appear to have
    considerable potential to provide a considerable amount of the
    nutrient at present provided by cereals in animal feeds.

  2. Although the materials refered to in 1. would appear to be able to
    completely replace the energy component in livestock feeds, they
    would be unable to provide other nutrients as well as cereal grains.
    However, the use of a combination of such materials with leafy
    material from the same plant, although reducing the energy component,
    could produce a blend of nutrients that could largely
    substitute for cereals.

  3. The lower protein content of possible alternatives referred to in 1.
    could also be compensated for by better utilization of locally
    produced protein sources, which are at present exported, or the
    use of proteinaceous agro-industrial byproducts, azolla, etc.

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